This does not sound right. If you don't change anything, DRMPro do not change navigation nor modify the length of play. It's even stranger that you tried both DVDs with still menus and both output exactly 4 seconds of audio.
If all of your menus are stills, would you mind post the original menu I'll see if I can duplicate. Basically zip all the IFOs and menu VOB (whether it is in VIDEO_TS.VOB or VTS_xx_0.VOB) only. Upload to some file hosting site and provide the link.
I'd like to see your
DvdReMake output as well. Do a test export since you say it behaves the same as a full export. Then zip all the IFOs and the menu VOB only.