When Outlook isn’t cooperating for you, is there any reason why you couldn’t log into Gmail directly and read & respond to emails? It may not be your preference, but at least it should let you do what you need to do. Just a thought. But hopefully you’ll find a solution to the Outlook situation.
Over the years I’ve had both Outlook and T-bird rather abruptly quit working correctly. But Gmail has been plugging along for, I think, about 9 years without a hiccup. Not that I’m too excited about having my emails sifted by them for marketing (and profiling?) purposes, but I haven’t worked up enough gumption yet to find something that might be better. Although... my son suggested that he knows how to set up an extra computer to act as a personal email server; if Hillary could have one in the bathroom, why not me? :)