Can not open most mkv since version 2.6.12

[quanghai]

Hi all,
Since version 2.6.12 (+13) I can't use the most of my mkv's.
Message: Attempt to open x.mkv failed ! Could not open the file.
If I reinstall Avidemux 2.6.11, everything works always fine.
But no more with 2.6.12 + 2.6.13.
If I remux the file with MKVToolNix without changing anything, then it works again.
Strange.
Is the problem known ?

[eumagga0x2a]

Please try the latest nightly build matching your operating system. If the problem persists, please reproduce it, then compress and attach Avidemux log ("admlog.txt" from %localappdata%\avidemux\ on Windows) to your reply or provide an affected MKV video as sample using a service like WeTransfer right away.

2.6.13 is extremely outdated.