Problem flashing back to stock tune file?

So I have a tune file from someone already in my car.
I have since purchased my MPVI2 and pulled the tune to make a few small changes to it.
I went to re-flash it and paid 4 credits and all has been well flashing it multiple times.

Last night was heading to the dyno and wanted to flash my stock tune back in for comparison purposes and it tells me I do not have a license for this file.

Why would it ask for credits to go back to stock? I have no problem flashing any other tune I make.
Thanks in advance

No idea really, unless the stock file also has another computer like the FPCM which you didn't license.

But that really doesn't matter. Just use the compare feature with your current tune and your stock file. Click compare again and down to comparison log. Collapse all the boxes and right click the engine icon and transmission icon to copy over all differences. Then save it under a new name, now you have a stock file again.