I've just run into a very similar problem - I have established a CA through Keychain access, and generated a CSR (only I did so through openssl on the command line) and attempted to issue the cert for the CSR through the process described above, with exactly the same result (endless spinner). On my first attempt, the process started Apple Mail, which I had not set up. So I set up my gmail account so there would be an active email account, but it is still stuck at "Finishing up...". This is Sonoma 14.0 on an M2 MacBook Air.
csarnows
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