Overlapped forms problem

Hello, I have a problem with overlapped forms after the export of the font. The merged version of the font looks just fine, but I need the version with overlaps as well.
The shapes were created in Illustrator, but I am more than sure, that the path direction are correct, I have tried inverting all of them several times, but the problem remains.

Here is what I have in Illustrator when I zoom the working area out.

This effect happens only in OTF version, meanwhile in TTF the overlaps look ok.
There is another problem, which happens in both versions and I do not know how to solve it.
Here is what happens to the M´s: randomly a black form appears. This form doesn´t consists of any vectors and cannot be deleted, but yet remains when the shapes are expanded.

Please help me to solve both problems.
Thank you in advance!

The overlap problem is a problem if Adobe’s renderer. Zoom out or zoom in a little, and it will switch into a different rendering mode. Nothing you can do about it from within the font short of removing overlaps, sorry.

The black shape looks like a hinting glitch. Perhaps disable hinting.