OP here. Still having similar issues today with Yahoo. I know I have messages which I can't reach.I've checked and rechecked the URL, and it's all correct. Remember, I stated that I have the same problem using Chrome browser, so Edge isn't at fault.
I'm getting a little annoyed with my Gmail accounts, too. I keep getting a message that my device isn't recognized (although I use it daily to check Gmail), and I need to have them send me a verification code on my phone in order to log in. Seems like 2 factor identification, but I never used that before with Gmail.
My least problematic email providers are GMX and Hotmail. If Yahoo problems persist, or Gmail begins to get too problematic, I'll no doubt be switching to GMX as my primary account.