Thanks for your replies!
I understand about the Save As as well as the Save on the hamburger menu on the Home screen. I should have mentioned that I had saved the document both via the hamburger menu as well as within the document (to cover all saving angles). And to reiterate, I was/am saving it to my iPad, not to the cloud.
The particular project I’m working on (for several weeks now), as I said is a several pixel layer document, black & white, basically a multi-layer “pencil” drawing - it is only 3000x2000px in size (300dpi). Saving the document has become the bane of my existence in very strange ways.
A couple of weeks ago I started noticing that it was taking longer and longer to save the file. So I thought I should try to merge some of my layers thinking that maybe there were too many. Funny enough, the merging seemed to take longer and longer, and so did saving the document... so much so that it was never certain if the document would be saved at all. For perspective, a month ago, saving took about 3-5 seconds. A week ago if it saved in 5 minutes that was fast.
By the way, as far as the merging goes... it seems like Merge Down or Merge Selected takes longer than Merge Visible (hide all but the layers I want to merge). So maybe this is another thing to look at?
I tried a few things... copying all of the layers then opening a new document and pasting them there. That seemed to alleviate some of the time for saving the document (whichever way I did it, either within the document or on the Home screen). In fact, I just did that copy/paste thing again and the saving/exiting the document is super fast - back to the 3-5 second range. I make duplicates of my documents, you know, just in case something goes awry... though sometimes work is lost and must still be redone.
As for the “crash” (not a crash as you said), it doesn’t always happen, and very often when it does, I usually only have one or two other apps open (usually Photos and Safari).
The saving (any way I did it) *was* working until recently. So I’ll keep backing up and tweaking my way through.
Glad to know that there is an awareness of the issue.