Q. Custom Fields on another add-on aren't working!
A. By design this add-on attempts to prevent information disclosure unless explicitly disabled. Unsupported content types may be using the custom field macro's unexpectedly.
Simply disable the template modification "Ensure custom fields fail-closed and do not display during updates" as a workaround. Yes this will disable the protection against information disclosure when upgrading.
Q. Is there an XF1 version of this add-on?
A. There is an unsupported XF1 version:
Custom User Fields Permissions