Unable to unmarry Cobb from ECU, before loading .hpt file!??

Currently the tune on my ECU is a Cobb stage 3 OTS tune. I am having issues, when trying to switch back to my factory (Ford) base tune, to unmarry my Cobb Accessport from my ECU.
The Cobb Accessport goes into a fault mode and then all I can do is return to a file tune already loaded on my Cobb Accessport.

To date, I have not registered my HPtuners Interface to this ECU, nor attempted to write a tune to this ECU.
I have used my HPtuners Interface, to read settings and data log my ECU.
I have registered my HPtuners Interface to my diesel truck, read factory base tune and loaded modified tune to the truck's ECU, without any issues.

My question, did I do something to cause the problem??

Thanks!

Have you created a support ticket with cobb? I think only they will be able to help you here

I've talked with Tech Support and they gave me a few things to try, but it didn't seem to help. Planning to talk with them again when I return to my shop.

Cobb typically locks the bootloader when installed, and you wouldn't be able to overwrite the Cobb tune with HPT anyways. So you're kinda stuck with it and dealing with Cobb to fix it... without getting a whole new ECU etc.

Connecting the mpvi and reading/logging some stuff would not affect the Cobb tune at all.

Thanks for the response! As soon as I get back to my shop, I plan on calling Cobb again, hopefully they can talk me through it.
I'm also considering purchasing a second hand, backup ECU and loading my original factory tune (should have a copy on my shop computer) to it. Not sure how difficult or possible this might be??
I know the replacement ECU will need to be cloned and the key will need programmed, but I'm not sure what else is required!??