When inherited, it is reasonable to expect the tags added by the parent to be reflected in the children. If the parent is editted after the children, however, tags that are added or deleted are not reflected until the tag container on the child is modified. Resaving or recompiling the BP does not correct the issue. Possibly relates to [Link Removed].
Similar to the aforementioned tracker:
1. Create a GameplayEffect BP. This is the parent
2. Add a Target or Asset tag component
3. Add a tag to the added field
4. Create a second GE BP that inherits from the parent
5. The parent tags should be visible. They can be cleared, they should still appear in combined.
6. Add a new tag in their stead and save.
7. Add or remove a tag from the parent and save.
8. The child now has stale tags. Saving or compiling will not fix this, only editing the container will.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-204855 in the post.