Very likely, Ilford have stated very clearly that MGIV isn't developer incorporated. It cn't be processed in an Activator solution.
Originally Posted by zumbido
For high speed processing Activators use Hydroxide and a high pH, typically developing in a few seconds, I think my Ilford machine took under 15 seconds seconds to process a print, about 3-5 in the activator
Originally Posted by Ray Rogers
The fogging came from having no restrainer or a sulphite and was a base gray chemical fogging, commercial activators contain Sulphite & usually bromide, but my first test were with plain NaOH.
But for normal tray use then a lower pH is of course fine.