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A licensee reported some of their particles disappear when setting the actor's custom time dilation 0.
This seems to happen when a particle is using PSA_Velocity as Screen Alignment.
This repros in 4.12, 4.13, and 4.14.
1. Open the attached project that has a character with two particle systems, both of them are using PSA_Velocity as Screen Alignment
2. PIE and press 1 to set custom time dilation 0
3. Particles disappear
4. (press 2 to see how changing custom time dilation from 1 to 0 affects these particles)
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-39423 in the post.