.mkv shows 0 seconds length in wmp library

When you play an .mkv by double clicking on the file it will open in wmp and show the correct duration of the file and you can adjust the playhead(fast forward, rewind). If you open wmp first and the same .mkv is in the library it will indicate 0 seconds. When played it will have only current time and if you touch the playhead it will start from the beginning again.
      I know this sounds petty when you could just double click the file and it plays as expected. But I would like a
fix because this 0 seconds seems to be causing some dlna devices to then not see the files in wmp server. I think this is just a key missing in the reg because the length is listed in explorer correctly, its playhead in explorers preview works as expected, and opening this file in wmp/mpc-hc is ok. Just the wmp library seems to be missing the Length and thus also causing dlna to not see the file. Much thanks for your work!!!

Just checked and the same exact scenario with .vob. These files are also associated with wmp, thus opening when double clicking on them. 0 seconds in wmp library

This is a limitation of WMP library. It may happen with any file type that WMP does not support natively.

There are two workarounds for proper playback:
1) Play the file by clicking on it in Windows Explorer instead of opening it through the WMP library.
2) Add the file to a playlist in the library. When played from a playlist, the duration of the file is shown correctly and seeking works normally. Note that with a playlist I mean an actual saved playlist, not the Now Playing list of WMP.

For DLNA it is better to used other software. For example Serviio.

I really need this fix for dlna to see the file on the server, this is the main problem. The two workarounds
for playback in WMP do achieve correct length of file and proper control of playback position.
      I hope these non-native files can be supported fully by WMP library by making some edits to the windows registry. Similar to the fixes made to Windows Explorer for the preview pane showing video playback for
none supported files and the status bar showing all the codec info. I believe this was thanks to Icaros and
the "Codec Tweak Tool" Please add WMP Library fix for unsupported files

I can't fix it. If it could be done with a registry tweak it would have already been done long ago.

There are other free DLNA servers out there that are much better than WMP.

Ok, I have downloaded and installed Serviio and BubbleUPnP, will see how it goes. Thanks for your suggestions and quick replies!!!!