In splitscreen, Material node SphereMask causes Material Billboard to only be visible to first player's viewport.
Found in 4.22 CL# 7053642, 4.23 CL# 8386587, 4.24 CL# 8557439
The material billboard will be render incorrectly as soon as player one looks away
The material would render as expected regardless of if player one can see it.
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-80096 in the post.