Opening a Niagara emitter or system permanently caps editor frame rate

Development Rendering
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1

Opening any Niagara emitter or system asset caps t.MaxFPS to the asset’s sequencer playback rate (default 60fps). The cap persists after closing the tab and across PIE sessions. The only workaround is manually pausing the sequencer or running t.MaxFPS 0 in the console.

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2

Steps to Reproduce

  1. Launch the editor with t.MaxFPS 0 (uncapped).
  2. Open any Niagara emitter or system asset.
  3. Close the asset editor tab.
  4. Run t.MaxFPS 0 in the console. Reads the asset’s playback rate instead of 0.
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3

Hi Claud,

Thanks for reporting the issue. I’ve tested it in different engine versions and looks like the bug is in all of them.

Will report it to the team directly so they can work on a fix.

Would you like a quick engine fix or you are ok with waiting for an official release?

Best Regards,

Joan

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4

Thanks Joan. We’ve managed to implement a local fix: stopping Sequencer playback in FNiagaraSystemViewModel::Cleanup() before resetting the pointer, and restoring OldMaxTickRate in FSequencer::~FSequencer to match the pattern in UMovieSceneSequencePlayer.

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5

Looks like this issue has already been solved in the ue5-main (development) branch, so initially it should be integrated in UE 5.8. Would you like me to ask for the fix commit so you can integrate it directly into your engine?

Best,

Joan

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6

Yeah, that would be great. Thank you.

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7

Hi [mention removed]​,

Here it is the fix commit:

Github: https://github.com/EpicGames/UnrealEngine/commit/78abb3b8cc41

CL: 48235381

Best Regards,

Joan

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