Well the reason to assume it’s graphics based is because 0x00000000…18 is typically associated with that.
You can’t really assume it’s the timer manager any more than you can assume it’s:
LevelTick
GameEngine
LaunchEngineLoop
Launch
LaunchWindows
exe_common.inl
As they are all mentioned here in the same way.
You said this is a BUILT project, correct? Like an executable file?
I know I’ve heard somewhere about the AntiAliasing settings having a possible issue with less-than-newest graphics cards, but I couldn’t tell you which setting would have been the issue. Possibly FXAA? If it’s hard set in the project before export, that could also explain your testers having the issue as it’s a problem across many cards, if I remember correctly.