Any update to this?  Interested to find a solution to the seatpost slipping issue.

Hi yes, good news.
After that mess with carbon paste and greasing the sliding surfaces (the tightening screw is yet to be greased), my system seems to be stable for now.
I did my first fun race this weekend in Luxemburg at "la Charly Gaul". It was ~112km and i hit a least one really big hole in the street.
I though, ok that was too much, I bet it slipped now.
After the race I checked the hight and it was still were it should be.Finally... BUT To be honest, before the race it re-tightened to 11Nm.
I would prefere to only do 8Nm and stay in spec.

For the creaking, i have to check that again. When riding along with so many people, its generally louder all the time.

More stripped paint and marks.

I drowned the post in Dynamic Carbon Paste... may a lot help a lot. Maybe i put on too less in the past.

Torque over spec to 10Nm again

I think a generous amount of carbon paste will prevent slipping.

Unfortunately not.
My bike now 400km and I re-clamped the seat post ~5-6-7 times.
Its installed with Dynamic Carbon paste.
Its torques with a Wera Torque wrench to 6, then 8 and the last two times with 10Nm.
Its clamped on the wannabe grippy paint (which is now stripped of, because of slipping).
It is really annoying. I will email Carol tomorrow asking for options: another clamp or seatpost or both or just hammering 20Nm on it, i dont know.

Took my bike into a new mechanic today and straight away he said he thinks the bottom of my seatpost is knocking against the seat tube when I’m climbing seated (which is the main time it creaks, stops as soon as I stand on the pedals), he’s seen it before, so likely he will cut it a bit shorter.

I cut 60mm from my stem, but it still creaks. But i think its the standard LCR Bottom bracket thats pretty cheap.
Will change it to Praxis Works one.
Or what would you guys say is a good, fair priced T47 BB for Shimano gear?

I totally agree with you.
Just go ahead and take the HBR14. Simple, cheap, its proven to work...done that on my bike. No issues, if you can handle to good look ;-)

I now have somewhat over 100km on my bike. Standard cheapo BB is already making noises.... meh
I think i will go for the rotor BB and put some shims between my BB and the carbon frame to prevent the BB from eating my frame.

Edit: Saddle slipped again at 240km with 9-10Nm... it start beeing annoying at this point.

For those who hear rattling from the inner storage area, check the pull tab on the storage bag zipper. It makes a surprisingly loud sound when it hits carbon.

See... i am not the only one. I just wrapped some brake hose anti rattling foam around it.

I imagine that a conical spacer in the right size can help fit the ortlieb axle.
But I have no idea how to measure it out which dimensions it should have.
If you have experience in that, this would super cool.

So measuring the Cone of the axle as first step.
That should be easy, because its size should be written somewere. Or i just measure it.
I dont know how the Ortlieb axle looks like. Can you show a picture?

have you clipped it in properly.  should be very snug.  Are you sure it isn't your cables rattling?

Yes, 100%.
With the foam on that cover, it is quite now. The brake cable is housed in anti-rattling foam.

@ All
Take a closer look on the HBR17 vs the HBR14 handlebars.
HBR17 looks a bit  in real world. If HBR14 was standard, i guess no one would take the HBR17 voluntarily

I haven’t ridden it much yet—only about 50 to 70 km so far.

Moving from my trusty old mechanical 105 to the Ultegra Di2 feels strangely nice and surprisingly good.
I absolutely love it.
Don't get me wrong, my 11-speed 105 setup is excellent; it shifts crisp and clean, but it is nowhere near as quiet and smooth as the Ultegra.

Building up the frame and bike was pretty straightforward.
However, what I didn’t like was tightening the bottom bracket cups against the carbon frame.
There was some slight abrasion during tightening. I really wish there was a steel washer between the cup and the frame. The current setup just doesn’t feel right or durable.

Setting up the brakes on this frame is also much harder than on my aluminum Radon R1—it’s quite strange.
On my Radon, I simply loosen the caliper bolts, squeeze the brake lever hard, and torque the bolts down. The brakes end up nearly perfectly centered.
Doing the exact same thing on the LCR18 just doesn’t work at all. Are the hydraulic hoses extrem stiff brand new. I dont know.

I initially torqued the seatpost to 6 Nm, but that didn't hold. It slipped twice during a ride, even though I used Dynamic carbon paste.
I have now tightened it to 8Nm, hoping it stays this time.

The thru-axles do not feel high-quality either.
I can already tell they will fail at some point.
It’s a pity they aren’t standard axles but use a proprietary cone shape instead.
LightCarbon should switch to a more standardized solution.

The internal frame storage was rattling like crazy. I had to glue extra foam inside to stop it.
I hoped i works nice from the factory, but forr me, it didn't work out of the box.

Finally, the bike is 2-3x as vulnerable to crosswinds as my Radon R1 ( round tube aluminium bike).
It is incredible how much of a difference there is.
While I was actually considering 65mm deep rims for my Radon R1, on the LCR18, I would now rather run shallower wheels with 40mm depth.

The frame is nicely made and the painting is incredible for that price.
The storage and the things they ship it with are super.
There are lot of good things, but its only fair to tell the complete story, with all its downsides as well, for people considering buying it.
I heard they also raised prices.
I would order again but ask for more standard axles and holes.

How come you decided to cut your seat post? Judging by your build photo, your seatpost is not really that far in. How far in is it now?

My seat post is nearly fully inserted, up until the anti slip coating stops.
Its squishing the DI2 cables unnecessarrily.
I meassured the distance were the seat post says "minimum insert". Thats 103mm.
I cut of 60mm and still have insertion of lots over 100mm.

Other people here reported a clicking sound whilst higher loads. I had the same on the first ride.
I hope the clicking is away now. Didn´t ride today.

I also contacted the suppliper for seat torque. They say 9-10Nm.
Unfortunately I have now all torques besides the Garmin-Holder for the handle bar. Anyone knows ?
I guess around 3-4Nm.

I run the cheap bottom bracket from LC.
If i replace it, i will go for the Rotor one i guess. Unfortunately shimano doesn´t do one.
I would trust shimano and pay for it, but there is none.