The little disclosure triangle to the left of an open database, used to display the groups etc in that database, sometimes disappears, as in the lower (open) database in this screenshot:
Does the database contain any groups/smart groups/feeds? Which version of macOS do you use?
Yes, the database contains many groups; also some smart groups, some of which came bundled and some I created. Some of these smart groups developed different coloured icons as I mentioned elsewhere.
I’m running macOS 10.14.6 (“Mojave”).
This has happened before, once or twice (not sure if it was to the same database). I right-click to close the database, then open it again, and the disclosure triangle reappears.
If this should happen again, then please choose Help > Report Bug while pressing the Alt modifier key and send the result to cgrunenberg - at - devon-technologies.com - thanks!