Product and version: FileMaker Pro 14.0.3 (but it's happened in 13 also)
OS and version: Mac OS El Capitan (also happened when I had Yosemite)
Description: Some when I go into Edit Layout mode, when I click anything all of my themes and styles on that layout will disappear. It's very frustrating. I have to then apply styling to each field all over again and hopefully remember which styles were on each field. It happens to me on my Mac version of FM and also to a coworker on this PC version. I really think it's a bug because it doesn't happen every time. I just recently upgraded to FM 14 and was hoping this wouldn't happen to me but today is the third time it has happened this past week!! So annoying.