Got this issue three times and reshaping it always fixed the issue. Changing a stock or mag is quite cheap (2.5k glimmer). A possible trigger for the issue: try to reshape the gun, but don't finish it and instead quit Relic (I managed to replicate it both times I tried). It seems that the devs are working on it right now because I'm no longer kicked when "something funky" message pops up in DIM.