I've installed 5 ER9 groups in the last 2 weeks. 1 gave me issues for some reason, but it was my fault. Make sure the limit screws are set properly, as well as the 3rd screw that sets the tension on the cage. The RD protects itself very quickly, so if any of the 3 screws are off, the cage wont shift. It's given me a new appreciation for my own incompetence and the fact that stuff usually works as long as it's installed and setup properly. During the builds i'm often thinking "this is such POS" but then an hour later, or a week later, i realize it's just me being incompetent / thick / tired.
Did you unplug and reset? battery's charged?
If you remove the wheel, does the RD shift? Are both FD & RD running the latest firmwares?

I'm planning to build my e-gravel with this group.
Would you mind to explain the known issue(s) of the group, as there are already 30+ pages.
The "dielectric grease" intrigued me 

I havent looked at geometry charts, but the seatpost looks a bit like a triathlon seatpost with the ability to move the saddle mount fore / aft. But if that's the case, by how much? a triathlon seatpost would typically have much more play.
And so from that, is this supposed to be a bike that lets you sit more vertical vs BB, like a triathlon bike would?
The shape of the seat tube is reminiscent of the Giant Trinity, so is it just looks, or is that bike you can dial in more than typical road bikes to lay flat and go fast on?

Short review of the updated ERX version from ChinaCycling.

youtube.com/watch?v=tq-Jat7ZmGQ

They mention the eGR having no issue with waterproofing, I believe that the learnings would be transferred to the road groupset?

You are definitely putting me on some gems with your findings. I've been looking for a saddle like this but couldn't find one that wasn't just full on carbon. Will definitely have to try it out. Also going to try Serenade Wheels during the summer.