Steve on 14 Oct, 2020 03:52 PM
welcome to the GPGTools support platform. Sorry you are having problems using GPG Suite.
The message you are trying to decrypt is in Rich Text Format (rtf). RTF is formatted text which tends to destroy the structure of OpenPGP messages and by that renders them useless.
To exchange OpenPGP messages use the Plain text format (txt). To switch to txt open TextEdit > Preferences and select the "Plan Text" option. For keys we recommend to use the key servers to distribute your public key or, if that is not an option, use txt or asc file format.
Can you then retry to encrypt and decrypt some test text and see if that works as expected.