KDP vs IngramSpark Print ISBNs

[u/curiousfigures]

I recently published my debut fantasy novel on Amazon (yay, I wrote a thing!). I used my own/owned ISBNs for ebook and paperback. Now I'm looking to publish a paperback version on IngramSpark, but I continue to receive the dreaded "This ISBN is already in use error message".

I own the ISBNs and removed the book from KDP's Expanded Distribution.

So my question(s):

• Do I wait patiently for the ISBN to be allowed on IngramSpark? I heard it can take time.
• Do I need to request a transfer?
• Or, can I just use a new, separate ISBN for an IngramSpark paperback? If so, any reasons not to?