MKA track length problem

Hi, been using MKVToolNix GUI for some time now converting multichannel .DTS audio files (usually 5.1 DTS-HD Master Audio) to .MKA. I've done this because it's always given better audio track playback and metadata tagging in media players. Proper track positioning / skipping etc. All was going well until more recently, I noticed that my MKA files now report incorrect track lengths. Much shorter than the original .DTS files. I've observed this in all media players playing the MKAs while the original DTS files report the correct length, as does the software that extracts them from source discs (DVD-Audio Extractor). I've updated to the latest version but still the same problem. When I convert the files, I make no changes to anything, I just drag the DTS files into MKVToolNix and then run Start Multiplex. Any idea if this is a genuine issue? Running v78.0 x64 installer on Windows 11 22H2. Thanks.