I'm not sure why, but after I upgraded to the second to last version (and it is still an issue in current version) I lost the Ctrl-M shortcut for toggling mirror browsing. It works through the menu option, but not via shortcut. No global items use this shortcut, and nothing happens when it is pressed.
Has anyone else seen this? How can I help debug this issue?
Tell me what additional info I can give to assist.
However, after seeing the "Reset All" button in Customize keyboard panel, I clicked that, then OK. This activated this keyboard setting. Not sure why that was necessary, but this fixed this bug for me.