Yeah this issue has been much weirder to address then the original one with the Viewport sizes. If we can absolutely rule out any Graph execution as you say from any other thread while being here in ::RenderRegions() on the RenderThread, that would narrow down the case quite a lot. Although, in this case, narrow it down to what else exactly.
I managed to dig up one of these IsValid() crashes sent from on-set, alongside the log and the minidump. Let me know if you get 5.4.4. symbols working on the minidump. In the log you will see in one of the the last lines the assertion which fires within the original FScreenPassTextureViewport Constructor.
In terms of crash frequency without our hotfix, it’s similar to the first crash, i.e. non-deterministic and might or might not run for hours or even over night. The frequency from one week’s test meaning one test per day, I would say probably similar occurence frequency than the viewport extent crash.
[2025.05.13-15.11.35:317][320]LogWindows: Error: appError called: Assertion failed: InTexture.IsValid() [File:D:\EngineBuild\Unreal-Engine-5.4-ICVFX\Engine\Source\Runtime\Renderer\Public\ScreenPass.inl] [Line: 148] No worries at all Rus, I am happy to help to make these things more stable in vanilla. In the meanwhile I am keeping our patches for our build. Once all of these cases are addressed in Vanilla we can then stop maintaining our hotfixes, which is always nice.
Best,
Markus