Custom OG Reference fields missing from OG Admin Fields UI

After following these instructions to create custom Organic Group reference fields, the custom fields disappeared from the Organic Groups Fields Admin UI. The fields can still be viewed and modified by editing the field settings on the content type/manage fields page, but after creation and upon returning to the OG Fields Admin UI, the custom fields no longer appear. See attached images.

My guess is that the Admin UI is querying for specific machine names?

For reference, I'm including my original comment about this, from the same referenced thread:

... Per my comment #62, in my install I'm not seeing custom OG references/relationships in my Groups UI at admin/config/group/fields. The same relationships are accessible through the Manage Fields UI (and Views) for each content type, so they are perfectly usable, but they disappear from the Groups UI (where they are created) as noted above. Assuming it's not just me, of course. I'm guessing this is due to a query looking for specific machine names?!

The reference/relationship did show up within the Groups' Fields UI while I was creating them, but then disappeared when I returned to that page to verify settings. I may have cleared caches in the interim, but can't say for sure. At this point I have created three "custom" groups references, and although perfectly usable and functional, none of them appear in the Groups' Fields UI.

and:

I'm guessing this is due the machine names of the custom OG Audience fields not being recognized by that UI? ... If true, I'm assuming we need to enforce/prepend a machine name prefix, then query by that?

It was suggested I create this thread as its own issue. I'd be happy to contribute a patch, but this is a little outside my current skillset with the OG ecosystem.