Is the temp drop and flocculation effect also true for lager yeast? In my experience an active lager starter will not settle in a 40 F fridge, for example. I always have to let the yeast ferment most of the sugars before it starts to flocculate.
Yes and no, there is strain dependency for the varying conditions in the beer. If a 10F drop in temp caused flocculation in all strains that would solve a lot of headaches
I have read that in some lager strains flocculation actually increases as the temp goes up to ale fermentation temps. I've also read that 50F is optimal in some lager strains tested, and that flocculation can be inhibited in some lager strains when it gets very cold. It is also inhibited by the presence of sugars, so actively fermenting yeast are less likely to drop out even when there is a temperature change, which explains your experience. And then there are all of the other factors that affect flocculation in a strain dependent way, like pH and ABV. Bottom line is you have to know your strain.
The 50F number is kind of interesting - it implies to me that the proteins/complexes responsible for flocculation may be very similar in ale and lager strains and they are structurally affected or maybe expression is repressed by the temperature. If you drop an ale strain 10F from fermentation temps and it floccs out, you are nearing the optimal temp that was found for lager flocculation in some strains. If you drop a lager by 10F from fermentation temps you are inhibiting flocculation by moving away from the optimum. This is conjecture of course, but it would be fun to study.