Not sure whether that is the issue and just flagging it as a possibility.
DosDude stopped updating the Mojave Patcher long before he stopped updating the Catalina one. The Catalina Patcher has the current MouSSE kext but the Mojave one does not.
Note that updating this on Mojave is not a case of simply replacing the installed version as the Patch Updater will nag you to update when it notices the installed version is different from the distributed one as it assumes different means older.
The twist is that you must never accept the option to ignore the message as all future checks (on everything) by the tool will be skipped and not just checks on MouSSE. Basically a bug. Important...Never accept that option. It disables all checks and not just for the item that generates it as you would expect.
You need to follow these steps to get the latest version and skip the nagging while keeping checks on for other tools:
MP3,1 (& others?) SSE 4.2 emulation (to enable AMD Metal driver)
Pending updates to the backend by DosDude, I have overridden the patch updater to allow using recent MouSSE versions without warnings as attached below. Download and extract attached FixPatchUpdate093.zip or FixPatchUpdate095.zip file for the MouSSE version upgrade This will expand into an...forums.macrumors.com
You will need to always repeat the process after using the Patcher following every software update.
I have modified my Patcher to avoid this.
You and @joevt are HEROES! Thanks so much ?