Arbitrary position for measure number in imported ver. 2.x scores?

When ver 2.x scores are imported, measure numbers are in an unexpected position:

This is how the score looked in ver. 2.3.2 (with parameters of the relevant text style shown)

and this is how it looks in current master:

One aspect is that the X offset in the ver 2.3.2 score is ignored, but this is already reported in another issue.

The most important point here is that the vertical position is wrong (too low) even if the vertical parameters are correct (-2sp offset, bottom alignment).

Furthermore, the Inspector for a measure number shows units in mm rather than in sp:

which, with a stave space at 1.8 mm, would approximately match the visible result.

So, what is going on? Are mm or sp? Is the original setting considered or ignored?

A small test score from ver. 2.3.2 is attached.