Are we talking of EyeTV 4 (8520) on a mac with MacOS Mojave 10.14.6 ? Okay, than I found a workaround. As I also couldn't find the export to mp4 I took the original .eyetv file of the record and converted it with iSkysoft Video Converter Ultimate (11.6.2) to mp4. This works perfect. Maybe, that it works as well with other video converters such as Movavi Video Converter Premium, which is nearly the same program.
Regards,
Manuel