How did you set up he watch only wallet in the first place?
You need to go to your coldcard and export json for watch only wallet, and then import it to your blue wallet I guess it was done in this way initially.
Give it a try.
Discussion
Correct, I did that initially. When I do that now though, it looks like there was never any bitcoin sent to the coldcard wallet. I can add the seedphrase into bluewallet to recover, but then I no longer have a watch-only wallet, it's a regular bitcoin wallet on bluewallet. What I am trying to figure out is if I can send my funds from this regular wallet on bluewallet back to a watch-only generated by the coldcard. I am not sure if I need the coldcard to sign the transaction or not.
Tried once more and it worked!
Your coldcard is a signing device, it holds your private keys in an airgapped environment. If you pasted your seed phrase into bluewallet, it now has your keys and they are no longer airgapped as the Blue wallet app has now accessed them.
They both have the same receive and change addresses derived from the same seed phrase. You should make sure you are able to spend the coins from Bluewallet, after confirming that, you can reset your coldcard and create a new wallet with it. Use the recieve address from the newly generated wallet and send the coins from blue wallet to tgat address.
Once receievd, uou can copy the json of the new wallet and create watch only wallet with it in Bluewallet.
Be very careful when making sure you can spend he coins in Bluewallet.