Thermometer off - low OG?

Ugh. Kicked-out of kitchen for almost a year. Got back in and thought I would try BIAB. Added 15% grist to offset expected lower gravity. Should have been 1.067. I got 1.050!!!!!!!!!!! Couldn't believe it.

All three thermometers off. Was mashing probably around 154*F from mash-in on. So beta-amylase is restricted, but alpha should have been fine. Would this higher temp really explain a 16 gravity point miss? BTW, iodine test showed conversion.

???

I've never brewed BIAB so I can't tell you why the gravity was so far off, but I wanted to tell you I clicked the link to your website and it is really nice. Good job.