Encrypting a stand-alone Windows file with sender's and recipient's public keys. When done using Kleopatra GUI, the recipient's tool reports that the only key used was the sender's (and since it doesn't recognize that the recipient's key was also used, the recipient is unable to decrypt the file). When sender encrypts with both sender's and recipient's public keys using either GPA (Windows) or GPG (DOS cmd-line), the recipient's tool decrypts the file correctly... only Kleopatra output files exhibit the problem, and only when encrypting standalone files. The clipboard method of encryption for the same two keys works.
Sender: 3.1.8-gpg4win-3.1.8 5.55.0, Gpg4win (Kleopatra) on Windows 10 Enterprise
Recipient: GPGTools/GPGSuite on MAC OS