It sounds as if you had logged into your existing Priority Pass account. You need to create a separate account for each Priority Pass membership.
If it had only been so easy.
When I wanted to sign up for PP with C1, I had to sign into C1 and add my VentureX CC # to even get to the PP registration page. I did not enter PP via any other portal.
The first 3 pages of the registration went without a hitch. However, on the 4th page, where I had to reenter my CC# was where the glitch occurred. PP had the right card company (Visa) but underneath that, where you entered the CC#, it was already filled in with my Amex Plat number, and grayed out for good measure, just to make sure I couldn't change it.
To solve the problem, I had a 3 way dialog with PP, C1 and myself.
The ultimate solution was to have PP register me from their end and fill out all 4 pages. That then required me to change my PW since I had to use a PW to register. It was a mess.