Just a small point, yeast make the precursor alpha-acetolactate which is is oxidized outside of the cell and turns into 2,3 butanedione (diacetyl). Yeast can't reabsorb the alpha-acetolactate, but can absorb the diacetyl and use it as an energy source later in fermentation.
It there is alpha-acetolactate in the beer, exposure to O2 can turn it into perceptible Diacetyl. I've had this happen.
Hop creep is known to bump up more Diacetyl. Some hops have enzymes that break down higher sugars into fermentables which cause the yeast to ferment more, creating more alpha-acetolactate, which then forms Diacetyl. You need enough time after dry hopping to let that clean up.
I don't do much of a Diacetyl rest these days. 55F for my lagers at end of fermentation, then slowly take the temp down, hold at 40 F for a week or more, then slowly down to -1C. Lower temperatures, but longer times.