I can’t prove it, but I’m convinced that doing an Admin-> Repair on any of the JS files causes permissions to be changed… and that can break your install of SuiteCRM.
I could not get the Calendar to display. I did a repair of the JS files and minified files. That broke much the application… I could not edit Leads or Accounts and other various buttons would not work.
I changed everything in SuiteCRM to 777 and it all started to work again… even the calendar… I then changed the permissions back to what they should be 755 and 775 as instructed in various posts in this forum.