Hi Michele

Are you talking about a button group created via

Administration → Advanced Customisation → Button Groups

Or the 'tabs' option under Administration → Customisation → Opportunity ?

Hi!  :-)

The button group created via Administration -> Advanced Customisation -> Button Groups.  A button that was created previously just stopped appearing on Friday. 

I moved the functionality of the button to a Global WF action so the client could keep working.  However, I cannot determine why the original button won't work.  I put the same criteria on the Global WF button and it appears when it is supposed to.  Any assistance would be greatly appreciated.

Thank you!

The Button Groups are associated with a particular System Action.  Check that the Button Group is associated with the correct action.  Check that there isn't another Button Group associated with that action.  If necessary delete the Button Group and reinstate it, adding the options again.  Test the buttons without conditions and then retest with conditions.

Check you dont have a button group for the same action more than once. I think this can cause this.