Niagara Component is considered for GetActorBounds With "Only Colliding Components" Enabled.
Found in 4.20 CL# 4369336, 4.21 CL# 4613538, 4.22 CL# 4666322
Steps with attached project:
The niagara component will be included with the bounding box even with "Only Coliding Components" set to true
Only the mesh would be included.
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-67882 in the post.