If you have multiple mastercam keys make sure the one you are using in you're computer has a lathe seat if it's a lathe part or a 5 axis seat if it's a 5 axis part. Otherwise you will get the "no operations were selected. please select at least one operation" message. I hope this helps!

Kind of strange but I figured out how to get the thumbnails back. I went into windows settings/Apps/Default apps then scroll down to the bottom and select Choose default apps by file type. Searched for .mcam and reselected “McamVersionSelector Executable” even though it was already selected. Then in file explorer I selected the view tab and selected “options”. Then inside the view tab I toggled “always show icons, never thumbnails” on and hit apply and then turned it off and hit apply and the visual icons reappeared. Hit the refresh button in file explorer if needed. I had to do this when I switched from Mastercam 2021 to 2022.