There seems to be bug involving niagara emiter and system timelines. While timeline is playing and jumps back to beginning there seem to be some sort of input given to engine. It closes drop down menus, stops mouse inputs (like holding down RMB when moving around in viewport and actual player movement while playing in viewport) and clears/deselects value inputs. Found in project migrated from 4.21 to 4.22 but not sure if that matters.
Easy way to replicate: Create niagara system, let the timeline play with lenght near 0 and try any of above
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I’m having the exact same issue and it wasn’t a problem in the preview builds of 4.22. Hope this can be resolved soon as it makes Niagara extremely annoying to use. The only work around that I have found so far is to pause the simulation while I edit values and close any Niagara systems before I play test.