The action bar still shows after a reloadui / relogging even though I unchecked the 'show' option.

Which action bar? All of them or only the main "Action bar" one?

All of my bars remain hidden after reloading UI if 'show" option is unchecked.

Only the main one. But for some reason (I didn't change any addons or anything) now the bug doesn't happen anymore... so sorry for bothering you, if it happens again I'll tell you but atm I can't reproduce it.

The only thing I changed is using 'action bars ext' (the reason why I wanted to hide the base forgeui actionbar), so maybe there was a conflict somewhere.

I remember fixing this bug for the main action bar few versions back. It's possible you had old version of ForgeUI.