I had the same problem while using ch throttle quadrant, stopped using that for any throttle input, just used my ch yoke problem was gone, not a great solution but at least that annoying ap disengage was gone so I i live with it now and only use throttle quadrant buttons.

OK I am at FL 200 on VATSIM and aircraft will not climb past 200 on VNAV even though next target is FL270 plus speed WILL NOT increase even though I have throttles at 102.6 N1Help must be a bug!?

Another possibility...do tou have your gear retracted? I once forgot and flew almost whole flight with gear down in FL240

OK I am at FL 200 on VATSIM and aircraft will not climb past 200 on VNAV even though next target is FL270 plus speed WILL NOT increase even though I have throttles at 102.6 N1Help must be a bug!?

Disable Fsinn weather.

Try opening FSUIPC then click OK without making any changes. If A/C assumes LNAV and VNAV commanded flight start a ticket with PMDG, they are working on it. You might also try opening the Saitek Control Panel and leave it running in the background. Both of these "fixes" seem to work though we don't know why.

Rickb1293 that was EXACTLY it thank you very much, Open FSUIPC-> Click OK then ALT INTVI hope PMDG fixes this tho;

I have the PFC throttles and have frequent A/T disconnects. One thing I notice is one engine is 10% N2 more than the other one and that's why I get this AT disconnect - even though both were at the same level a minute before. It seems 1 engine will surge or creep causing the imbalance and the subsequent A/T disconnect. One thing that works (sometimes) is after A?T is set,I move the throttles to idle or full so they can't go off balance. This sometimes helps.

Paul,Check your dead zones and calibration. I don't use PFC but twitchy flight controls are almost always caused by setting your dead zones too tight. Do you use the registered version of FSUIPC? If so, check your axes settings and calibration.Good luck.