What should I buy to make sound synch on ATEM TV studio?

I purchased a ATEM TV Production Studio and want to use the internal H264 capture directly to my laptop.

Everything works fine except the audio drift. I am shooting seminars and at the beginning, everything seems to be in synch,.. but the longer it goes, the more the lips are out of synch with the sound.

I am on a Mac.

What inexpensive hardware do I need to buy to fix this?

Thanks

What software version are you running?

We found using media express with the latest TVS drivers and recording at 3.5mb MP4 we could record for over two hours without sync shift. If we dropped down to 2MB we did get sync shift. BM suggested using an older set of drivers but to be honest the 3.5mb works for us. Make sure you also have the latest version of media express installed.