Hi all, thanks for your suggestions. I ended up having to use Apple Support text and was then transferred to a phone call for someone to help brainstorm. That ended up working. I wish I could list out step by step what we did but I don't think I'd get it right.
What was similar to prior suggestions:
I did have to turn off Mail in iCloud (Settings > Apple ID > iCloud > iCloud Drive (listed under Apps Using iCloud) > Click on third box "Apps syncing to iCloud Drive" > Mail - toggle off
What was different from prior suggestions was that, once the above was done and the signature was created in "All Signatures", I had to click and drag the "Signature 1" (or whatever you may have chosen to call it) into iCloud (listed underneath All Signatures at the left). Exit Mail. Open Mail. Then I had to go into a mail message (which at that point didn't have the signature listed but did have a box listed next to the From: line that allows you to choose a Signature. Signature chosen.
At that point we may have exited and opened mail, then turned iCloud Mail back on. I can't quite recall. Good luck!!