ReadyDLNA cannot allocate memory while scanning mkv file

I have an ReadyNAS Ultra with RAIDiator 4.2.28 and has a similar issue.

A lot of my mkv-files is not able to be added when scanned.

Also tried a manual scan through SSH, and got the:
metadata.c:686: warn: Opening /c/media/Videos/High Quality/MOVIENAME.mkv failed! [Cannot allocate memory]

I have tried to remux the mkv with MKVToolNix, tried to rename it, and a lot of different things.

It does not seem I have space or memory issue either:

nasHOME:~# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/md0 4176564 353596 3613308 9% /
tmpfs 16 0 16 0% /USB
/dev/c/c 7767758348 2671212232 5046546116 35% /c
/c/media 7767758348 2671212232 5046546116 35% /home/ftp/media
nasHOME:~# df -i
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/md0 65536 9411 56125 15% /
tmpfs 127616 1 127615 1% /USB
/dev/c/c 121856000 56506 121799494 1% /c
/c/media 121856000 56506 121799494 1% /home/ftp/media

nasHOME:~# top
top - 10:17:59 up 20:20, 1 user, load average: 0.00, 0.02, 0.05
Tasks: 96 total, 1 running, 95 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.3%us, 0.7%sy, 0.0%ni, 99.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 1020932k total, 739544k used, 281388k free, 41488k buffers
Swap: 524272k total, 532k used, 523740k free, 535732k cached

What can be the issue? (And how can I fix it?
The MKVs plays fine through SMB