I was wondering why my concentrated developers were consistently less active than the identically-formulated ones directly mixed into water (without the PG carrier). Was I damaging the developers by heating the PG solution to 50C or with the extra handling? So I formulated one in water, developed a test-strip, then added 3.7% PG (by volume) and dev'd another strip. Significantly thinner, more than the extra 3.7% dilution could cause.
Did you let the developer sit in a flask and see if there is any phase separation? (Like salad dressing made from oil and vinegar)