asserion Error when importing a file with a different sample rate from workspace

[Inglesworth]

Running PT 10.3.10 HD on OS 10.9.5. I am absolutely aware that is not officially supported, etc. However, I have not had any consistent problems with it (until now) and it's been running for over 2 years at this point.

All of a sudden, when dragging audio files from the workspace that are a different sample rate than my session, it gives me an offline clip and I get an assertion error in the task manager. I could import these files into a session a week ago with no problem this way. I can import the same audio files by dragging from the finder or doing the good ol' Shift+Cmd+I.

Nothing on my system changed recently that I can think of, so I am not sure why it is suddenly happening. In the past, Assertion errors have been fixed by trashing preferences, etc. No luck. I have confirmed that SRC on import is checked in the preferences. I have tried setting it to automatically copy on import, I tried turning that off to see if it made a difference. No dice.

Anyone ever experience this? Any ideas on something to check?