Niagara System No Running Preview

[mjdstudios]

Hey everyone, using Unreal 4.27.

Im having this issue where my entire Niagara System is broken after being completely fine up until the point I discover it. I ran into this issue before and just created a NEW system and copy+pasted the emitters from the broken system into a new one. For what ever reason, this fixes it. But this is not an ideal solution.

Here’s all the things I’ve tried.

• As said before, pasted everything into a new system. (this works but not ideal because it’s not the first time this has happened and this is a big project)
• Dropping in fresh emitters into the system. Still broken
• Changing properties and recompiling. Still broken
• Deleted everything in broken system and added new emitters. Still broken.
• Disable and re-enabled emitter. Still broken

Has anyone encountered this and know how to fix? This sounds like a very nasty bug that is an Unreal issue.

[ClockworkOcean]

This could be a bit of a long shot, but try clicking once on the viewport and CTRL-R?

You may have inadvertently turn off real-time preview. Works for levels and materials also…

[mjdstudios]

So that was not the issue. What we found out was that the whole Niagara system was in a corrupt state. But we were able to fix it by going to the build drop down menu and clicking Full Recompile.

This is still an issue that pops up in our project however. Niagara systems becoming corrupted for unknown reasons. We still have no clue what causes this, but it’s annoying an frequent enough to be concerning.