Yep, I have also found this to be the case... I guess it will be fixed sometime.....
There seems to have been several things that FileMaker 13 doesn't do so well in Mac OS X 10.10 and I'm sure a lot of it has to do with FileMaker 13 being developed when 10.9 was the current version.
Other things I notice is that a number of short cuts went away, probably the most annoying to me is command-L to go to Layout mode.
Also, occasionally, FileMaker just freezes and I have to click into Find and back in to FileMaker and all is good then. But it happens regularly when doing development work such as going in an out of editing layouts. It seems less of an issue to end users.
Of course I'm hoping FileMaker 14 isn't too far off either!
When the keyboard shortcut for layout mode disappears --- and I have been unable to figure out what causes it -- several other keyboard shortcuts disappear too, among them: duplicate, group, ungroup, new record, sort records, omit record and others I probably don't use often enough to miss them. Oddly, though, new request appears twice in the requests menu, once without a shortcut and once with a shortcut I've never seen before for New Request.
This issue, by the way, is not limited to Yosemite. It was happening in Mavericks, too, just not as often and not as egregious.
I am also experiencing problems when I have multiple windows open (belonging to different files) and I select certain things on the current window, like the drop down list to change "modes" (Layout/Browse/Preview/Find) as well as script steps in script maker and a few other places. When I click on certain things, it behaves as if I would be clicking on the passive window behind the active window, - it shows the options as per what you would expect from the active window, but in the location where you would expect to see things happen on the passive window... weird and annoying.
some of the shortcut experiences are documented here:
I see strange behavior with color picker in conjunction with text attribute all over Yosemite, 'specially with Apple Notes, Mail and Pages