Your problem is that you want to convert the other recording to mp4?
I ran into the same problem myself, but I moved the "recording.conf" file out of this holder and then did a manual conversion and it worked.
Convert using the Zoom desktop client
For versions 4.6.10 or higher, you can't convert local recording files by double-clicking the Zoom files. You must follow the steps below to manually convert the files:
Sign in to the Zoom desktop client.
Click theMeetingstab.
Click theRecordedtab.
Select the meeting topic with the local recording.