We are getting multiple crashes on 5.8.1 when trying to use the cinematic viewport on Linux (tested on Kubuntu 22.04), the most consistent way it’s been reproduced is by clicking on the blue frame number to the left of the cinematic viewport transport controls. After some investigation, we believe this is a Linux specific memory handling issue between two duplicate definitions of the SNonThrottledSpinBox type between MovieSceneTools and LevelSequenceEditor. We’ve also seen crashes less reliably when closing the editor with the cinematic viewport active, and we believe this memory issue is the same root cause.