Percussion stems do not follow definition in drumset when ties are used.
In the attached file I have defined the stems for the bass drum to default to up.
When I enter a single note the stems point up as expected.
If I use the + key to add a tied note the stem points down.
I get the same results for all tested non-pitched percussion instruments.
This happens in both versions 2.1 and 2.2-dev 871c8ce. Not tested in 3.0.