GPU particles not colliding in-game in all my existing maps

I’ve got a simple particle system which pushes GPU particles (with Collision) down onto a basic plane. In all cases, the particles bounce in editor. In my existing maps, made in 4.0 and copied to 4.2, the particles will not bounce when playing in game, even when I replace the ground with the exact same simple plane. In all new maps I create, the particles successfully bounce in game. I’ve been diligent to eliminate any other possible affectors, going so far as to strip my existing maps down to only the plane and the emitter.

What has changed? What can I do to my existing maps to make them work with GPU collisions?

Later in the evening I found similar behavior with regular particles and the Particle Attractor module. When I place the effect in one of my old maps which were updated to 4.2, the Particle Attractor doesn’t work. When I place the effect in a new map, it does. I’d love to know if I need to throw out my old maps and start again or if there’s a fix.

Hi lackthereof0 -

Thank you for your report. I have tried to reproduce this issue and haven’t been able to. My particles work as intended when I copy my 4.0 project to 4.2. Can you let me know exactly what versions you are using for this, so 4.0.0 or 4.0.2 and 4.2.0 or 4.2.1 and whether you are using Launcher or GitHub compiled versions. Also exactly how are you updating the project, a copy or a convert in place?

In the meantime, please be sure to review our suggestions for how to report a bug, and feel free to edit your post if you have additional information to provide:

How do I report a bug? - Programming & Scripting - Epic Developer Community Forums

Thank you.

Eric Ketchum

Hey lackthereof0 -

I am marking this answer as closed for tracking purposes, but if this problem has persisted or returns please feel free to comment with the information requested above and we will get back on trying to correct this issue.

Thank You -

Eric Ketchum

The fix turned out to be to type “RecreateLandscapeCollision” into the in-editor console. The landscape collision was corrupted during the migration.