PSBT load error: Unable to decode PSBT.

1. Test PSBT in your wallet today, create a transaction in Bitcoin Core and click. "let go" and "unsigned generation"Then "Load PSBT from…" The menu displays an error.

   PSBT unsigned tx has empty scriptSigs and scriptWitnesses: Unable to decode unspecified iostream_category error.

I have no idea what happened. However, the same procedure works well for other testnet wallets as well.

Neither wallet is just for watches.

2. BTY, what is the simplest way to test and confirm that I am the owner of the fund other than sending actual coins?