I can understand you use case, but I wouldn’t consider this as a bug. Group, FX and VCA Channels are only automations, nothing more. And if you hide all tracks in any folder, even the folder becomes hidden.
These are also an automation tracks. So again, it works as specified.
As I said, I understand your use case and I agree, the feature doesn’t meet the use case you want to use for, as it is designed now. Maybe I would recommend to make a thread in the Feature Request thread, where you can specify your use case.