If you search this forum, you will find out that dock compatibility is generally quite a fragile thing, kinda like silicon lottery, so you are already quite lucky that it mostly works 
You may update a community-maintained list here: USB-C/Thunderbolt Dock Megathread
Regarding your issue, it would be very interesting to test it on Windows also (or at least another distro) if you happen to have a copy at hand: if it works there without problems, it means it’s a Linux kernel driver issue probably, otherwise it may mean hardware/firmware incompatibility.