Description
When using the [is (dynamic)] [One of My Groups] filter on a glide list referencing sys_user_group, the condition evaluates to false if the list field has more than one value.
Cause
This is expected behavior as the dynamic filter [One of My Groups] only expects a single reference and when a glide list field has more than one item it would be sending two references and fail.
Resolution
You can manually script the condition to check if you are a member of the groups in a Glide List using an array loop.
Here is an example from our Docs on how you can get and loop through the values in a glide list: Reference a Glide list from a business rule
Then you need to run each value returned against the isMemberOf() function for your user object: GlideUser - Global