I have ran into the same exact problem. I have tried copying events, creating new ones, and even random things like changing browsers I was using to access or Joomla Editors. All did nothing to help resolve this issue.
There are NO red tabs that show up to mark an error with the input. Nothing conflicts with another event, however it won't save a repeat in day information now and even items like Show Detail Link, Show Attendee Buttons, Duplication Prevention Override, Override Global Overlapping Check, Exclude Event from Overlap Check all won't save the parameters on repeat dates as well.
Help would be greatly appreciated on this topic as it seems as though Spike and I may not be the only ones with these issues.
This didn't happen on the previous release and yes we are using the current release of 2.7.4
Same here - big issue for me - have been waiting for the shopping cart functionality that was new to 2.7.4 before going live - but now will prob have to delay again becuase of this as we have daily repeating events that align to school terms in multiple schools - so creating each one indivually would be a massive overhead.
i had 5 repeating events, deleted them and wanted to make new ones... now the repeating events are not saving... my site has to go live tomorrow.... HELP.