midi sync problem

[Michael jonathan]

hello
i own a Korg Pa4x my problem is like this :

when i connect my pa4x via usb cable to my computer DAW ( i use Ableton & Logic)

and make the settings from the global menu "pa4x midi clock sync to usb"
the pa4x is then in time but the problem is the EFFECTS like reverb or delay
i hear crackle cracks and pops like audio distortion...

this has nothing to do with audio latency ..im shure because i have connect my pa4x as slave direct to my roland groovebox synth with 5 pin midi cables
still the problem was excist even without any daw.

... this problem make it imposible to work with the pa4x...

and sometimes i have hanging notes special when i try to edit the notes from the piano roll window on my DAW..

any help would be great

thank you