"Random anything" is a wholly undiagnosable issue. 4.12.11 resolved a
regression in 4.12 which caused EDID to not be read properly over DP. There
have been many reports of this causing a variety of issues.

Sounds like your issue is wholly unrelated to the original issue reported here
as well. When in doubt, file a new bug. Marking bugs as dup is trivial.
Untangling separate issues from one bug is impossible.