Hi,
every addons that try to track regen spells on players (as mutagen) at one point or another fail.
Many times addons fail to catch the event (regen on player) and as such don't show anything.
The fact that EVERY addon shows this behavior, makes me think there is a problem in your API (and it's not the only one, but this is another story
)
Now, I really don't understand why you don't want to give your players a better UI, with options to downgrade it to a minimalistic UI, but at least give us a working API.
Regards