Mathematica v 12.1.1.0 FrontEnd Autoformatting Bug (?)

I also ran into similar problems with 12.1.1 for Mac. Check the MD5 checksum of the version you are using. There was an initial version posted when 12.1.1 was first released that contained some front-end bugs. It was rather quietly replaced with a revised version of 12.1.1. The MD5 checksum of the latest version, which seems to work much better, should be: 8f8dadb67974755bc4a5935393581e5d