David, unfortunately I cannot offer any help, but just wanted to include my experience with using my published 10.7.1 address locator as a geocode service within Web AppBuilder (non-developer edition). It has not worked well because it appears to use only the first locator in the composite, and if the second level locator never gets applied then some addresses don't geocode correctly. Not sure why it behaves this way.
Using the address locator (not the geocode service) in ArcMap on a file with street addresses works great and applies the best locator of the two in the composite.