Yes I have the same issue. I manually started all over in 3.4 and I have 16 printers so it was a couple of hours as I did a few and walked away from the computer and I used the new backup plugin which works great and kept adding a couple of printers, backed cura up and closed cura and reopened. For some reason after the 14th printer if I add another printer backup and restart cura never reopens. Then I have to delete the 3.4 folder and it does a hard boot comes back open shows me all my printer profiles from 3.31 and the list is really long and it ask you to reset your profiles but it only has a reset button and doesn't give you an option to say no. If you don't reset every time you open 3.4 its still there and in front of your build screen so cura is worthless unless you click the reset button. After that its like a fresh install. Using my back up I'm able to get it back working with only the 14 printer profiles so I'm sticking with version 3.31 until someone fixes this. Not sure if 3.31 is causing this issue and I have to have both up to enter in my settings. I haven't tried print screening the settings and only have 3.4 open at the time. It worked with no issues until that point.