Atem Mini Pro (iso) audio not in sync with Rodecaster Pro

I use the monitor L/R line output of a Rodecaster Pro to feed the Mic 1 of the Atem Mini Pro (two 1/4" TS plugs to 1/8" TRS). But this introduces a high pitched noise that, if I turn up the gain in post, presents problems.

I then try to align the audio that recorded with the Rodecaster, but this does not stay in sync for longer than a few minutes. Any idea on how to either 1) Get rid of the noise during recording or 2) have the audio files sync up better?

Right now they only stay in sync for about 5 to 10 minutes max before I have to make an edit and shift the audio.

It has come up many times here in the forum. You will need something like the StageBug SB6 from Radial Engineering. But there are many other manufacturers that make products like this.

You will need to feed the outputs from the Rodecaster to the inputs of the StageBug with two balanced TRS cables (link). Then from the outputs of the StageBug with one unbalanced cable with two TS jacks to one stereo mini-jack (link). Make sure the audio level in the ATEM Mini is set to Line Level.

Thank you so much for the detailed response.