Designer is putting in abbreviated message path, which isn't working

I’m following along quickstart for Jmix (just to see how it differs from CUBA - not much, but still), and putting in the captions for the talks table/calendar, the designer puts into the XML an abbreviated path, for example msg:///table.caption - which will then be highlighted in red as an error and not work in the running app.

Looking at working captions, it seems the full path is needed now - for example

It seems the way message packs work was slightly changed with Jmix vs. CUBA.

Yes, now the localized message mechanism works as you described. The usual work of localized messages will return in the next plugin version.