Page Provider failed to handle multi-value complex field

Page Provider failed to handle multi-value complex field in predicate. Slack conversation:

Should I be able to create a Page Provider predicate against a multi-value complex text sub-property? I get this error:

Uncaught exception: com.google.gwt.core.client.JavaScriptException: (TypeError) : Cannot read property 'Nm' of null
    at Unknown.VVf(studio-0.js)
...

When I 'ok' the error dialog, and cancel out of the predicate editor, studio is greyed over and I need to reload, losing any changes I have made.