Onebar shows on a horse but it just disaplays above the normal food and health along with the horse hearts

That is probably Flour's Various Tweaks' "Mount Hunger" setting, just disable that. OneBar already has that feature anyway.

Ahh, I see, it has no toggle, so I reported the issue to the dev.

Thanks for the help you've provided with my problems.

You're welcome. Either way, closing the issue as it can only be fixed on their side.