BeerBorg

I've never had MoreBeer pils LME not attenuate like I mashed it myself, so that is kind of werid. What yeast did you use?

Two vials/packages of WLP800 - fresh.

It fermented at 54 for 2 weeks before being raised to 65 for a D-rest/finish for 5 days. It didn't move after day 10 or so in terms of gravity.
After that I dropped the temp by 5 degrees/day until I hit about 38 for 3 days before kegging.

I have no clue. I often get close to 78-80% attenuation when I use MoreBeer Pils extract depending on my yeast choice (it's why I like it). Maybe you got some weird batch of it.