Here is the recording from 2 different channels. I am getting 5 of these channels on VHF Hi.
It sure sounds like DMR. Strange that it doesn't trigger a DMR decode and mutes the digital audio.
Check again that those channels actually are set the same way as the ones that do decode the DMR signal. Try to set Threshold to manual and 8.
If you push the "channel" button to stop scan and then enter the frequency and then hit "channel" again it should decode DMR. The threshold setting for that mode are in the menu for Srch/CloCall Opt.
I know that I have problem with super narrow FM modulation that some ships are using, that are more narrow than FM and NFM. The audio level are too low to start to decode in the 536. Do Fn+CHANNEL and continue to push "CHANNEL" until you come to NFM and use that mode.
The most sensitive setting for threshold are 5 so try that as well, but it will also be the setting that creates the most false decodes but are good way to try and see if the signals modulation are too weak for a normal threshold setting, usually the one that auto will end up with after a few seconds.
/Ubbe