Flatpak app autostarting, then disappearing from autostart list

Hi, there is an issue with I have with autostarting the JamesDSP audio enhancements app - when I add it to Autostart, it boots up at system launch, but then disappears from the list, meaning I have to re-add it there if I want it to start at the following boot. This is on EndeavourOS, and the app is installed via Flatpak. Is this a known issue with some apps? What is causing it?