Photo files (ONPHOTO) spontaneously delete themselves

After editing an ONPHOTO file in ON1 Photo RAW 2020, the file is spontaneously removed from my MacMini drive on the next attempt to save--it's there, it's opened, it's edited, it's saved, it's spontaneously deleted with no trace. This is a recurring, transient problem--sometimes it fails to save the initial edit, sometimes it's deleted after 1 edit, sometimes after more edits. The issue did not exist for several years (approx 2021-2023), only in the past year, when I upgraded to MacOS 14 and 15.