Sour Kettle Berliner Weiss - No Fermentation

I recently Soured a Berliner Weiss wort for 2.5 days to a PH of 3.7 with lactobacillus (WLP 677). The wort was then boiled for 90 minutes and cooled before pitching hydrated US-05. It's been over 60 hrs at 65 degrees and I do not have any signs of fermentation. There is not a problem with the fermentation bucket or seals. I'm assuming that the Low PH is causing a problem for the U.S.-05, however I'm not sure as I've never performed a sour wort before.

I suspect the low PH will also delay infections by other organisms, but I'm not sure.

Should I be considering an alternate yeast or Brett to get the fermentation going? Another approach would be to warm up the fermenter, I just hate to delay much further if it risks an unwanted infection.

I've been preparing to brew a sour wort berliner for the past couple weeks and one of the most common suggestions given about fermentation has been to pitch a big, active starter due to Ph.

I did not see any Krausen. Just a few small bubbles. Going to pitch a couple of vials of Brett.

did you take gravity readings? wlp677 is heterofermentative so it will not just create acid but also ethanol so you may have fermented it down enough that the US05 didn't have much sugar to work with and so you wouldn't see much activity. i've had similar experiences with champagne yeast where the 677 took the beer from 1.031 to 1.016 and i then pitched the champagne yeast but I saw almost no activity but it bottle conditioned just fine. i haven't used 05 with sour beers but 3.7 isn't really that low so it could be just fine. you can see my experience with 677 here:

http://www.hommelhomebrew.com/?p=7

Describe the process of making the wort? Malt bill, mash temperature & time, gravity before pitching WLP 667 and after, and gravity after boiling?