When using the Construction Script to remove instances with the Get Instances Overlapping Sphere function to get the references, the behavior of this functionality is different for ISM and HISM if a Sequence is being used for the execution.
If the Sequence is removed and everything is done in order, it works properly with HISM, similar to ISM.
Regression?: No
This occurred in 4.20
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-67685 in the post.