To my failed Metolal I added enough metol to make the original concentration 40g/L.The metol appears slightly acidic and I had to add some sodium hydroxide to the 1:50 working solution to increase the pH from ~9 to ~11.
The metol addition restored the developing activity of the failed Metolal and I successfully developed a test film in the working solution at pH 11.
Thus,in the failed Metolal,it was the metol that failed not the sulfite or hydroxide.In Rodinal, p-aminophenol would not be expected to fail so rapidly IMO.
Only one experiment but it does suggest that metol undergoes some oxidation or hydrolysis to which p-aminophenol is not susceptible.