Just transited through MIA last night from Bahamas and connecting to PHL. (4:30 pm)
Global Entry and immigration was a breeze even though numerous planes were in at the same time. Bags were even in quickly! Turn the corner to go through security for connecting flights and BAM! Long Disney style lines with the TSA lane shut down. At this point, only two scanners and 3 lines were running. I asked the one TSA guy about pre-check and he just said it's closed.
Over a half hour waiting in line