As discussed we do not notice errors for symmetric encryption properly. This can be easily reproduced by setting a libgcrypt 1.9 based version into symmetric mode. Kleopatra will think an operation is successful even if it failed. Which dould worst case lead to data loss as the text edit in the notepad of kleopatra is emptied after a (reportedly) successful encryption. But the error can also be reproduced with run-encrypt in gpgme without involving kleo so I am only tagging this as a GPGME issue.