Sleepy Gloss (Low sheen)

Sinkage into substrate, due to insufficient primer or undercoat, MDF paraffin wax contamination.

Solution

For MDF use Crown Trade Grip Extreme Fast Drying Primer after rubbing down, then re-coat, other surfaces may simply require re-coating.  Never apply a solvent-borne gloss directly onto MDF as it lifts the "grain".