filters/remeshing/subdivision surfaces:midpoint is sometimes not working right.
read in this ".obj" file
v 0 0 0
v 1 0 0
v 1 1 0
v 1.5 0.5 0
f 1 2 3
f 2 4 3
select the right-hand facet. then use the filters/remeshing/subdivision surfaces:midpoint menu option with default options selected.
result: the vertical edge on the left side never gets subdivided.
when i wrote my own code to do mesh subdivision, it had the same problem. i fixed it by always, at each iteration, subdividing the longest remaing edge, not just any old edge.
(also, if you hit "apply" about four times, you'll get an assertion error; see my previous bug report).
this is version 130a, 32-bit windows.
We are able to duplicate the bug. In the next days we will try to fix it.