It not uncommon for the pseudo to precipitate in a fluffy mass of crystals that crunch down a bit when rinsed. Down to a quarter of what they were... well, that does sound like a bit too much.
What was your total available pseudo HCl in the pills, and how much pseudo HCl did you have when the stuff in the filter dried?
And you did dry the MEK before using it, right?
The advent of Eudragit polymers in the pill mix made a serious dent in the usefulness of STE alone as a means for obtaining clean pseudo HCl. One of these polymers seems soluble in acetone and MEK, and acetone or MEK with that polymer in it seems to dissolve pseudo. This is particularly true of acetone, and not as true of MEK. I have found some success with drying the pseudo completely dry, then rinsing with dried MEK. This will discolor the MEK with a yellowish tint, leaving white pseudo. The pseudo, after this type of MEK rinse, no longer dissolves in acetone.
IF you poured your MEK into the mix with the solvents, just heat it up again and boil the MEK out again. Your pseudo will precipitate out when the MEK boils off. Use due care, of course. This time, when you rinse with actone, pour the acetone rinse through the filter and collect it in a separate jar.
If you poured the rinse into a separate jar, just evap the MEK and see what forms as it dries. Chances are you will have a yellowish tinty oily film on every thing. If you do, put the whole under a heat lamp and bake it gently to complete dryness. Then flash it with MEK.
This is obviously not a complete solution... it is a help, though.