Did you check the 3 point lift control valve? I just had to replace one on my L185DT. Happened out of the blue so to speak. Front dozer blade still worked, so pump was OK. Checked the filter and cleaned, and then cleaned the valving on the left side of the rear axle. Still no improvement. Took the rear axle apart to remove the control valve. I tried to take it apart however my age, lack of proper tools, arthritis and a torn rotator cuff, I could not get it apart. Was easier to get a used replacement and install it. Now have a working 3 point again. I am assuming that your 3 point was operating correctly before you cleaned the filter and replaced fluids. If so then you may have released some metal shavings to go downstream from the filter and stopped in the lift control valve. This is just my .02 worth.
Jackie