I finally got my addin to work but it only fully loads in my admin acct but not in my poweruser acct. The toolbar loads in my poweruser acct but without the combox and any toolbar titles. No missing labels are present. All is well in admin.
Pete...to clarify, is this the procedure your followed? Sharing and installing add-ins—Help | ArcGIS for Desktop
and the well known addin folders Essential Python add-in concepts—Help | ArcGIS for Desktop
and I think the material is a bit dated, since the operating system will have an impact, particularly for those that have migrated to windows 10
Oh yes...double clicked .addin file...said it loaded the toolbar in the dialog and then shows it in addin manager properly. But just a tiny single unit blank toolbar appears.