Thank you for this prompt reply.
I do not remember seeing the dialog you posted. I was intending only to update the catalog to v13 and there was a link on that dialog that gave me the opportunity to create a new catalog. Otherwise, I would not have created a new empty catalog. As proof, I am running v13.1 now after importing my 39,000 images. I did not do a separate update to my new current update. I did not run a process to create a new catalog. Therefore, I had to be performing an update to create the new v13 catalog. I have no explanation for this, it just happened the way I described it.
Importing the images into a new catalog will not carry over your edits from the old catalog, unless you had set the old catalog to automatically write changes into XMP. (you would still lose some metadata, like edit history, ratings and collections.) By default, all edits and other metadata only exist in the catalog.
It's hard to tell from your description what actually happened, but are you seeing your old edits in the new catalog?
If not, follow the procedure I outlined in a previous post – double-click the version 12 LRCAT file (old catalog), which will launch LrC, and present you with the Catalog Upgrade dialog, where you click Upgrade.
Alternatively, go to File > Open in Lrc, and navigate to the version 12 catalog.