Why isn't my PSBT considered complete after walletprocesspsbt and finalizepsbt?

I created a transaction using createrawtransaction spending a UTXO that I own the keys to and then converted it to PSBT using converttopsbt, then I used walletprocesspsbt and finalizepsbt. After finalizepsbt, my "complete" value is false.

Is there a way to get more details on why it’s not considered completed?

Thanks,
Francois