As another thought ... I do not think you have said you have tried using regular thread.
Perhaps what you need to do is try some FMQ with the regular thread, to ensure that you can FMQ without problems.
It could be that the monofilament is not the sole cause of the problems you are having.
With three threads going here, that it's hard to keep upwith what's going on, EllieGirl.
... would be much easier if you had kept it to just one thread, and the continuing story, IMHO.