When cold, mine would hardly move until I ramp up RPM to above 1500. Until then it was very slow. Still does, at times at 1100 hours. Mine seemed to have gotten bad after my first transaxle oil change.
One thing I noticed, when the dipstick showed 1/2" below full, it was actually 1.5 gallons low. After I topped it off with lo-vis it seemed better.
After subsequent oil and filter changes, sometimes when idling the tractor when cold it will move very very slow until I boost the RPMs above 1500 and when above 1800 it starts acting like it should.
Generally when warmed up a little all is good. Filters always look good with no debri.
I would be nervous with a filter sucked flat. Chances are it was crushed at install.
Mine seemed to get better after using it a few times and only is irratating at cold idle for the first minute.