Ok I got the drive to work after formatting it to ntfs. But some of my 1080p mkv videos stutter!
And the sound only can be heard if I use the TV’s default sound. I use a Bose sound bar which works perfectly with my PS4, but why doesn’t the MKV sound play through the sound bar as well?
That is because the PS4 can let you get only Dolby Surround 5.1 or AAC format if you wish. Something that your TV and/or your Bose speakers is able to decode.
But if your MKV file has a DTS HD-MA 7.1 surround, your TV clearly does not support it so you can try to let your TV do a passthrough. But if your BOSE speakers cannot decode the format, then of cos there'll be no sound. You are not the first person coming here to report of their Bose speakers getting no audio.
Remember. Certain DTS formats are not accepted by the TV so even if you try to get a 2.0 AAC signal for your TV to decode, it just will not do it.
Get a proper speaker that can decode such signals of the movies you want to watch.
Even my Logitech Z906 speakers are able to accept a newer DTS and Dolby format such as a Dolby Atmos 7.1 signal downscaled to 5.1 running via optical from the TV with the TV set to Passthrough.