Old SWF files suddenly not reading button code or syncing audio/video

Swfs that have worked for years suddenly began misbehaving in both the "test movie" and the published modes. Same odd behavior in the AIR app which contains them.

One swf in particular does not recognize all of the code that controls some of the buttons, while other buttons loaded into that same frame function as expected. I have about 15 files built on the same format, and all but this one function correctly - as they have for the same time frame mentioned in the first sentence of this post. Examination assures me that the fla files are still structured identically.

Another swf does not allow all of the buttons to even come into focus on rollover. Of 14 identical buttons installed into the same frame with the same code, 2 buttons behave as expected. The others behave like graphic symbols (visible but not functional).

Is there an update that messed things up?

I am not sure this is connected, but I am publishing for Adobe Air 26 (the latest version available in my Animate interface), but the swf files use Flash Player 30 in the "test movie" function.  I don't recall the details of upgrading to Flash Player 30, but I suspect that I was encouraged to update my flash player.

Any insight will be appreciated.