Possible routing issue- phase problem recording two tracks at once

I’m using Cubase elements 11.
On the project I’m having an issue with, we went back in to redo bass guitar.
Decided to get rid of the old tracks and create new ones-
But prior to tracking I accidentally clicked on my tv/monitor as the driver.
(Which was crazy because playback was really slow so it did something to the sample rate idk, needless to say I switched back to the interface, a UR22mk2)

We are using a DI just like we did before- wet and dry out
Mono in left and right side

Only now when I engage both some crazy phasing / feedback loop is happening

I’m wondering if my routing got messed up because all my tracks I already recorded were no longer assigned to stereo out.
But I can’t find the issue

The weird thing is if I pan both tracks hard left and right, the phasey sound is lessened
And somehow it’s also picking up the click and recording it to the audio.

I know for a fact I’m not sending an identical signal from the DI.

I mean I was a little tired so MAYBE I accidentally made two stereo tracks, and then chose the mono l and r input path?

Any ideas on where to look?
The worst part is I was so tired when I tried a restart, I saved the project.

Never had this issue before…

Did you turn on loopback on your interface?

oh I see it’s in the settings- enable loopback- I will check that and get back to you on it- I’ve never had to use such a feature, I’ll be sure to let you know if that worked

Cubase AI on PC does not have this loopback option where you describe it. Any place else to look. If you search the manual, there isnt even the word Loopback or loop back in it at all.

Loopback is a function of audio interface. It can be a physical hardware switch or this option can be found in control panel for the interface or its driver.

Well, with a few moves you could export/mixdown the track and split it to return to the Project as one Left and one Right track, then reverse the polarity of one track, then export/mixdown these two tracks and bring it back as a single mono track. It happens.