Bug, Mac OS issue, Virus, or Freak Glitch

[Check-1-2]

I've used the M4 successfully now for about 4 years.
Read everything before you respond to me, please...
About a week or two ago, I was recording a mic signal into channel 1 of the Motu M4, into DP (latest version).
My signal started to get weak and strong, like volume pulsing and cutting out every other word, and some fuzz that continuously bloomed louder with every time that you make sound into the microphone. A distortion that sounds fuzzy and buries the original sounding signal, but reacts directly to the voice going into the mic.
My first thought was - its the mic. So I swapped mics. SAME THING. I swapped mic cables. SAME THING.
Okay, maybe it was the channel on the M4, maybe channel 2 would be different? Channel two didn't make any sound!
I made sure it was all set up correctly in DP also (for anyone wondering, haha).
So I thought, maybe my M4 is broken. I ordered a new M4. It came a few days ago. I tried it out - same tests - and my NEW M4 has the same two problems!!! Channel one fuzzes out while it interacts with any mic. Channel two doesn't acknowledge input sounds or signals - it doesn't show bars moving. With the same mic and everything! with Phantom turned on like before.
Then, if I record in DP, I can get vocal signals tracking for about 15 seconds of clarity before it starts a fuzz-back chain... I can't tell - it doesn't have any routing or busing that would make it feed back. Fuzz back is the best I can describe it - Your singer is singing along, and gradually they sound like a fuzz pedal's amount, speed, frequency, distortion, feedback, delay, echo, and reverb are being turned up... you hear crackling glitchy fuzz and almost what's like a ring modulator. Its super weird.
I tried changing buffer size. That stops the symptom for about 30 seconds. It happens on absolutely any buffer size. Switching the buffer size back and forth every 20 seconds, singing about a line at a time, I was able to achieve one clear pass through a song. And when it plays back, its clean. But if I didn't do that, and recorded it - that bad stuff that happens makes it onto the tape. The fuzzy weird feedback reverb fuzz echo would ring and ring louder until it covers up the voice and even modulates the notes.
I've updated DP and it's still doing it. I've just updated my Sonoma, so I'll see what happens in a few minutes. Also I think I just reset the PRAM. This can only be: Power (of the Mac Book Pro) (Not the USBC cables - I've tested multiple, and same result), software (bug with DP), firmware (I updated the older M4 and the problem persisted), or, act of Cathulu.
This is puzzling.

[mikehalloran]

This can be many things that you haven’t mentioned. Are you tracking with any plug-ins? Where is your Input/Output blend control set? How are the monitor switches? Are you using Loopback? MOTU drivers or Core Audio? Direct connection or through a hub?

[Check-1-2]

Okay. Solved it with Sonoma latest update AND PRAM reset, and deleting system audio settings.
DP is working fine with the SSL 2+ interface... but I haven't jinxed it yet trying out the M4 on it again
Maybe I'll try that AFTER I get my work done

[Check-1-2]

This can be many things that you haven’t mentioned. Are you tracking with any plug-ins? Where is your Input/Output blend control set? How are the monitor switches? Are you using Loopback? MOTU drivers or Core Audio? Direct connection or through a hub?

Next time I am going to check these things as well. I'm not sure if it's cured or not. Hopefully it is.

... Direct and Hub connection - didn't make a difference on this. Tried both... Same result.
...Input and output blend was centered.
...It was just the track, no plugins.
...Monitor switches on the Motu's... switch for channel 1 worked... channel 2 was like DEAD.

I have to check the M4 tomorrow. But an SSL 2+ is working currently, no problems...

[mikehalloran]

This can be many things that you haven’t mentioned. Are you tracking with any plug-ins? Where is your Input/Output blend control set? How are the monitor switches? Are you using Loopback? MOTU drivers or Core Audio? Direct connection or through a hub?

Next time I am going to check these things as well. I'm not sure if it's cured or not. Hopefully it is.

... Direct and Hub connection - didn't make a difference on this. Tried both... Same result.
...Input and output blend was centered.
...It was just the track, no plugins.
...Monitor switches on the Motu's... switch for channel 1 worked... channel 2 was like DEAD.

I have to check the M4 tomorrow. But an SSL 2+ is working currently, no problems...

There's a big problem.

There is no such thing as zero latency. By blending the output 50/50 with the slightly delayed input, you have set yourself for phase cancellation and comb filtering. Twist the knob to the 11 or 1 o'clock position.