Something is very strange here.
When you click in the “save as type” box, MPEG-2 should be the 8th item on the list.
ATRAC audio
Audio Interchange File Format
Dolby Digital AC-3 Pro
Dolby Digital AC-3 Studio
FLAC
MainConcept AVC/AAC
MainConcept MPEG-1
MainConcept MPEG-2
All I can suggest at this point is to contact Sony Customer Service and see if they have any ideas.
Sorry 🙁