Being from Zürich, I have most of the David Zinman / Zurich Tonhalle Orchestra Albums. I noticed that in the roon database many of these only carry the David Zinman, but not the Orchestra Tag:
At this time the best option here is to select each of the albums from this Focus (you can do this with Ctrl+A/Cmd+A) and then selecting Edit. You can then add credits for all of the albums at once.
Thanks for the report, and apologies for the inconvenience!