I find melodic dictation grading is actually quite relaxed, the imitation is really tight. When on dictation you're 1/16 off it basically marks it as cool.
On imitation if you're even 1/32 or so on certain patterns, you're back in the doghouse. If anything relax the imitation a tad.

With the ...

yes, same problem here, with simple rhythms like 4/4 or 3/4 I can go 2 or sometimes even 3 bars ok, as soon 6/8 or something funny comes up, big struggle.

spent good chunk of time on it, still crap, what kills you is that the 6/8 metronome basically stops for 3-4 seconds after lead-in
and then you have to hit the first beat (on imitation). If you just miss it by a fraction of a fraction of a second and then carry that delay into the rhythm it grades ...

Let me emphasize that, it's worse than useless, it completely throws me off with the 6/8 exercises so then I don't 'feel' the 3/4 or 4/4 coming up after that.

Bluntly, if I would be a music teacher or could just 'feel' the music, I would not have bought earmaster in first place (which in fact is ...