Still trying to demo these in stores without much luck, even after reading these posts.
I'm assuming the high vaulted ceiling is blocking signal but it's one of those things you don't want to hinge a purchase on, ya know?
Most commercial buildings in my neck of the woods have steel roof trusses and heavy galvanized steel sheeting above that. In flat-roof construction, the additional weatherproofing is then supplied using either concrete or a few inches of mixed tar and gravel capped with loose gravel. Sometimes there's a maze of galvanized steel HVAC ducting hanging up there, too, and maybe some coarse wire mesh to help hold down the spray-on insulation against the trusses and ceiling interior. Suspended ceiling, too? Then figure another lattice of steel down below. Lots of random conduit and junction boxes for lighting and communications, too.
All told, that's not quite a Cheyenne Mountain level of radiation blocking, but it will definitely gum up any high-frequency RF signals that might be trying to get through, including GPS.