I tried setting up my iOS HDM with a Cold HDM on Android and it tells me the signed Server QR is incorrect even though I input the correct password on my Android and it gives me the signed challenge QR fine.

My Cold HDM Android is already registered as HDM Cold with another Hot Android HDM.


I am thinking my problem is either:
1. Using the same Cold HDM for multiple HDM setups is not allowed, causing the error.
         - There should be an error message explaining that this is not allowed.
or
2. iOS and Android HDM wallets are not compatible with each other.
         - I think they should be compatible, as many people might have an old Android but not an old iOS >7.0 device.

Edit: The problem was #1. If I wiped my Cold Bither and reset the Cold to a new Cold HDM, the pairing worked.