Steve on 07 Apr, 2021 11:06 PM
welcome to the GPGTools support platform. Sorry to hear you are having problems using GPG Suite.
The message you are trying to decrypt does not appear to be txt format but instead 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.
Could you then try to encrypt a new message and retry decryption.