Greetings,
I did a search and found some other issues with the spell checker, but I couldn't find this exact issue. If this is a duplicate, I apologize.
I am using all 3 programs Publisher, Photo, and Designer, on a Windows 11 PC/Laptop.
After I click to Add or "Learn" a word to my dictionary, it will stay until I close and then reopen the program. Then I almost immediately start seeing the red squiggle line under that word again. Two of the biggest added words that I noticed are "LLC" and "BOOFOLA" (a company's name). I do not know if Photo is doing this or not yet. I very seldom do text in my Photo program.
Thank you and I hope to see this fixed in future updates.