This may have been discussed before, although I can't recall seeing it. A tie on a note on the middle line of the staff (B in treble clef) will invariably be an under-tie rather than over, even if the stem is pointing down. This simply doesn't look right and I can see no way to fix it. Or is there? For now, I use a slur where playback isn't affected, i.e., when there is no accidental on the note.
I already sent a bug report, and I was assured that it was fixed for the version 1.60 release.
Anyway, there is a workaround: simply force the stem down instead of letting it down by default.
Yes, this is fixed in the next release. Stay tuned.