Update: Found the “Reset View” option, and that worked!
Running Axure Pro Edition v184.108.40.20661 on macOS Mojave v10.14.6
My Masters pane suddenly disappeared - not sure if I clicked something or hit a hotkey but was working in it, switched to doing something else, went to go back to it, and it was gone. I’ve checked that it’s activated in the View menu options and have tried toggling it off and on. I’ve tried toggling Libraries off and on and that works fine, also tried toggling the entire left side panel and that worked fine as well. I’ve tried restarting Axure… can’t seem to get it back! Anyone had this happen? Any thoughts?