White labs troubles?

Hey folks,

I've been brewing a sour raspberry wheat for several years now, using L. Brevis from White Labs in primary (via 1L starter @90°), followed by an ale yeast after pH is achieved.

Since January I've purchased 5 pitches of Brevis, and only 2 have succeeded in souring. The others never took off in the starter or failed to work in the carboy.

I'm sitting on the 5th right now, which failed to start for a week in the carboy. Out of frustration I tossed in Wyeast's Brevis and White Labs' Delbruckii, just to try to achieve sour. 24 hours later I have a krausen. 36 hours later, gravity dropped 10 points. 48 hours later, gravity holding steady. This whole time pH has failed to move.

My personal fermentation frustrations aside, have any of you had issues with White Labs recently? LHBS says they're the 'bottom of the barrel' for liquid pitches, but doesn't stock bacterial strains in any other brand. Getting tired of pissing away money on what was a proven recipe.