Dropping Frames upon Tape Export in FCP 7 / Yosemite

Hi all -

We have a new install of Yosemite on a 2013 Mac Pro, we've installed all the usual software, but also upgraded to an AJA Kona Lhe Plus card for our tape exports to HDCAM and Digibeta.

We are getting a drop frame error in FCP 7 now when using Edit to Tape to run Tape exports. This is happening for all tape exports. A screengrab of one of these errors is below.

We normally ran our exports (prior to OS and card upgrade) from a fiber connected SAN. But while that SAN is being upgraded, we are running Tape exports from a brand new local SSD (very high speed) - which is used for no other purpose - so we are pretty certain disk speed is not the issue.

AJA has been contacted but they claim they haven't seen this issue before. I'm thinking we've overlooked something after the reinstall.

Any thoughts or guidance on what the issue could be?

I've been having some trouble with small freezes in Yosemite recently. Maybe you're dropping frames due to something like this? Try opening your console (Applications > Utilities > Console) and see if you're getting a lot of recurring nasties. Also check your Activity monitor to see if something there looks a bit dodgy.