Problem with folder 3-pane-view in DT

Even after using the former setting again? Weird.

I have a different problem with 3 pane view - it may be that I should have started a new topic, but Iā€™ll press on
I have just bought a new iMac (M2). I installed DT3 from my old iMac (M1) and it worked fine.
I then decided that I wanted to keep M1 - 2011 version running High Sierra v 10.13.6 - and run DT3 on it as the second seat and at the same time share the data so that changes to one were reflected on the other - so that my assistant could do some tasks for me. That worked fine too until this morning
This morning I noticed that while changes on DT3 on M2 were reflected on M1 the view on M1 had changed using the See Also & Classify view. The Groups section was blank and the lower Documents section was showing the same data as M2. M2 on the same view shows both sections populated
Iā€™ve closed and reopened the app on M1, tried Option-Command-N and generally fiddled about on Preferences for both DT3 and M1, all to no avail. I canā€™t believe that it isnā€™t something pathetically simple, but this pathetic simpleton canā€™t find it!
Can anyone suggest a solution?

Welcome @chrbyr1

The Groups section was blank and the lower Documents section was showing the same data as M2. M2 on the same view shows both sections populated

A screen capture could be helpful.

As requested

Screen Shot 2021-07-21 at 10.49.28

According to the screenshot no databases are opened and there are no groups in the inbox, therefore thereā€™s nothing to suggest for DEVONthink. After opening the databases (e.g. via File > Recent Databases or by double-clicking on them in the Finder) this should work again.

Thanks, that did the trick! I hadnā€™t appreciated that while sync synchronises actions it doesnā€™t sync the databases that are open on the master Mac. Pathetic simpleton just about described it! We grow older and wiser, although I was pretty old to begin with!