Midi File Import problem to Dorico 3.5 with a Nuendo 10.3. generated Midi File

Dear Dorico Community, Dear Developers,
I have a really annoying problem:
I exported a Midi File from Nuendo 10.3 and wanted to import it into Dorico 3.5.1.
At first it generally worked, most of the instruments were recognized correctly.
However, one melodic track was, as it seems, irrevocably transformed to a singlepitched drumtrack and two percussion tracks were imported, but without visible data in them.
A countercheck in Sibelius worked correctly, all tracks were recognized and shown in raw, but correct form.
When trying to reopen the same, Steinberg-generated Midi File in Dorico I got the message that this is an invalid file format. Nothing I could do about that. I then went into Nuendo again and re-exported the same file.
Now I could import it into Dorico again, but with the same problems described above.
All of this is rather unpleasant and should not happen, right?

Please have a look at the files, if possible!
I have one hint: When exporting Midi Files from Nuendo or Cubase for Sibelius, they never were really recognised as such, I always had to allow ALL files, not only Midis, in the browser to be displayed for import before being able to import - but then they opened (in Sibelius).

And: Using Music Xmls is not an option for me in this case since I need to preserve microtimings and velocities.

Answers are welcome,
Thanks!

Best,
Thies Mynther

Which midi channel is used by the culprit track? I think channel 10 is “reserved” for drum tracks, that could explain the odd behavior… Maybe try and change that, if it’s the case?