Unable to "Create results as hosted feature layer view" with Join

[JasonCyphers]

I have a hosted feature, with two related tables, in Portal 10.8.1.  Since I'm unable to perform in-memory joins in ArcMap or Pro, to then publish to Portal, and our version of Portal (10.8.1) does not have the "Create Results as hosted feature layer view" option, I turned to AGOL...   I created a map and added the feature to the map via Add layer from Web, entering the rest URL of the feature in Portal.  From there, I attempted to join the feature to one of its related tables.  I can perform the join, but the "Create results as a hosted feature layer view" option is grayed-out, and I cannot select it.

This would be fine, if I didn't need to have the join view update whenever a new record was entered.

Any ideas of why I can't create the view (is it because the hosted feature doesn't live in AGOL?) or any ideas of how I can create a live, joined view of the data?

[jcarlson]

If they were layers in an enterprise geodatabase, as opposed to hosted, you could use a Query Layer to accomplish this. Odd that the option is greyed out. I am able to attempt this same procedure on my own data, but it fails to actually execute.

[JasonCyphers]

Only thing I can think to do is host the feature in AGOL, where I can create "live" joins; then, figure out a way to add it to a Portal map that can be edited in the field, without having to create an AGOL account for the field user and without sharing the feature on AGOL with the public.