An update for posterity: eight days after pitching I started seeing renewed fermentation activity, and kept rousing the fermenter once or twice a day. Two weeks after pitching, the SG is at 1.0200, which is a couple points higher than I expected, but close enough that I'm confident it did finally get down near the attenuation limit of the wort.
As much as I'd like to isolate the variable(s) responsible, I think I'm finished playing with 1214. I love the ester profile, but the combination of low flocculation, low attenuation, and inconsistent performance is a deal-breaker.