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 com.medflex.planner.screen.talk/table.caption
It seems the way message packs work was slightly changed with Jmix vs. CUBA.