It appears that saving from a secondary tab does not truly save the workspace. I thought I was going crazy, losing work even after hitting Cmd-S umpteen times to avoid the problem. This is what I found today (Using Version 12.3.4)
I am diagramming a paragraph at a time, but then consolidating everything in the first tab by chapter. So, I generally have the main diagram tab and a secondary one in which I am actively working. If I save from the secondary tab (Cmd-S), the Save option in the File menu goes gray but the file itself it not actually saved, based on the time stamp of the file. If I go to the main tab, and hit Cmd-S (I also found the File menu Save option is once again black, not grayed out), the time-stamp on the file is updated and the data is saved.
If the secondary tab is treated as its own document, where is it being saved? If saving from the primary tab saves the entire workspace, why doesn't a save from any pane or tab save workspace as a whole?
I have attached screen shots