Had the Bulk Edit app lock up, began by removing tenant permission and then removed from site contents. Reinstalled and icon was missing from ribbon bar but could be run from site contents page ok, no longer locked up. Followed recommendation above, twice, still unable to get the icon back. Only app issue now noted is that project owner cannot be changed without generating an internal error, so must change owner outside of Bulk Edit. But would like icon back. Requested help from Microsoft and they were unable to help.