I only wish I would have found your thread earlier 😉

http://www.sqlservercentral.com/Forums/Topic1415833-2799-1.aspx

We are experiencing the exact same behavior and have had a Sev-B case opened with MS on this for over a month now (currently escalated to the product team). Feel free to PM me offline if you would like the SR number.

We have been a dozen or more PSSDiag collections and have been dumping the ring buffer outputs for RING_BUFFER_RESOURCE_MONITOR and they do not show any new entries around the time when PLE dropped. Moreover during this timeframe, Page Reads/sec value do not fluctuate much indicating that we did not have to read a bunch of new pages into memory. The query with max reads around this time frame was 32K.