Thanks to your advice, I did check a bit more the clearance between the thrue axle and the end cap.
I took the same thrue axle to compare the clearance between : the XMCS front wheel, the XMCS rear wheel & a winspace front wheel.
There is definitly much more clearance in the XMCS front wheel than on the XMCS rear wheel orwinspace front wheel.
I will contact Peter and I'll let you know how

I did check the wheel cap inner diameter and it seems similar to the rear wheel.
The additionnal clearance is due to the front wheel "tube" being oversized vs the rear wheel one (see pictures).

I had the same but on farsports wheels. The noise is getting worse the more kms you ride.
Together with my LBS we identified the wheel caps and hubs slightly out of spec causing this. Farsports replaced the wheel caps and it solved the matter.

Thank you so much for your reply.
Do you know which dimension was out of spec ?

I did purchase and receive few weeks ago some 50 deep with 26IW with CX ray spokes with R248 hub in UD paintless.
They weight 1250g and feel very light on the bike.
Unfortunately, since I mounted this new wheels I'm experiencing a problem with my front brake (Ultegra 8170Di2 on a Lightcarbon LCR018 frame).
My front brake is sometime making a loud metallic noise while braking (not necessary on strong braking). This never happen before mounting these new wheels.
What is also strange is that it's sporadic : on some ride, I don't have noise for 2 first hours and then it start.
I did few trials to identify the origine of this noise and it seems to be related with the front wheel.
When I put back my old wheel (reinstalling the same disk) I have no problem.
I did try to install a new disk and new pads without solving the issue.
I did also try to use new resin pad (instead of metallic pad) + other disc without resolving the issue.
The disk is tightened with a torquewrench at the right torque (40Nm).
Do any of you experience this issue ?
I don’t really understand what could cause this : do you have an idea ?
I will also continue to try making other test (maybe test them on my other bike).
I'm not feeling vibration while I'm braking but the noise is realy not nice and I'm not confident going downhill with this phenomenon.

Finished the assembly on my frame without any issue 

First ride yesterday and got  issues that were discussed on this forum.
Integrated storage door that tend to open (as I was aware I did check regularly to not loose it during the ride).
After the ride I noticed that the small screw of the closing mechanism needed to be retightened. If this occur again I will add some threadlocker on it.
By safety I add a strap to maintain the door in case of problem : once the issue will be solved, I'll remove it.
I also have the saddle tilt and don't find a way to use my torquewrench to ensure the 16Nm. I tried to tighten it as strong as I can and will see.

First ride impression need to be confirmed with the right tire (I have ordered some 32 mm) : I installed temporarily some 28 mm tires but have some 32 mm in order (on my previous bike I have some 32 mm so of course the confort is not the same).
Anyway I noticed that I was much more confident with this bike in the downhill.
Still a big fan of the raw carbon glossy finish

Got a message that my size 56 with glossy raw carbon ordered end of November was finally shipped (originally was supposed to arrive end of January).