mkvtoolnix-gui improperly detects metadata of 22.2ch LATM/LOAS AAC file

Two files are being uploaded to aac\ folder in the ftp. Both are 22.2ch LATM aac files as detected by latest nightly BtnB ffmpeg builds:

Input #0, loas, from 'nishino.aac':0KB vq=    0KB sq=    0B f=0/0
  Duration: N/A, bitrate: N/A
  Stream #0:0: Audio: aac_latm (LC), 48000 Hz, 22.2, fltp

Input #0, loas, from 'sun.aac':    0KB vq=    0KB sq=    0B f=0/0
  Duration: N/A, bitrate: N/A
  Stream #0:0: Audio: aac_latm (LC), 48000 Hz, 22.2, fltp

They can be played with BtnB build of ffplay.exe, with the following command line:

ffplay -f loas -i sun.aac

However, when dropping them into 56.0 mkvtoolnix GUI, they appear like this:

This doesn't look right.

mkvmerge.exe sun.aac -o sun.mkv also produces garbage output (file is much shorter, I think it tries to mux it as 2ch or something else).

Thanks!