I've been making lots of lager recently, usually in the range 1C-3C for four weeks or more, and I'm not happy with the way some of them have finished. I'm confident that if I leave them long enough they'll carb up eventually, but it's taking way too long, not fully carbed after four weeks and no end in sight. I wouldn't mind but it's not even helping with clearing the beer, looks like something that fell out of a washing up bowl.
So much so that for the next few brews I'm going to completely change my priming routine by batch priming and adding fresh yeast to the bucket at the same time as the sugar. Might try a neutral ale yeast and leave at room temperature to see if faster carbonation adds or detracts from the end result.