I've narrowed this bug down, previously posted in the 12.0.410 forum. This is more succinct.
Using uPnP server, with video files > 2Gb (which almost all feature length movies are, has the following bug:
The media player (in my case, D-Link DSM-520) displays the current position and the total length of the video. When you direct it to "jump" to a position more than 2Gb from the start of the video, the timer displays correctly but the video jumps back to position 0, the very beginning.
I believe there is a 32 bit integer variable being used, which would have a range of anywhere from -2,147,483,648 to +2,147,483,647. When the upnp server is told to jump to a position > than 2,147,483,647 bytes into the media file, it overflows, and instead jumps back to position 0. I think it should be an easy fix to use a 64 bit integer variable instead, which would make it virtually impossible to not be sufficiently large a number for any foreseeable media file.
Anyway, that's my opinion as to the problem. I really hope it gets fixed quickly, because I really like virtually everything else about this product and want to be able to use it for my home media system.