Greetings and Happy New Year!
Tpday 01/01/200 faced this issue after auto update the FIP-FS (filtering management service) on our on-premium server MS Exenge 2016 21 KU with the latest security updates (KB5007409).
The FIP-FS "Microsoft" Scan Engine failed to load. PID: ХХХХХ, Error Code: 0x80004005. Error Description: Can't convert "2201010001" to long. (2201010002, 2201010003 etc)
Since the service is interconnected with the transport service, mail stops coming in and out, respectively.
And yes, as a workaround, disabling Disable-AntimalwareScanning.ps1 helps