Concrete tile roof bubble?

Anyone know what this is? It appears to be a bubble. About 90% of the tiles on the roof had this to some degree. They were all at the same location about 3 inches from the bottom of the tile but they varied in their location right to left. They sounded hollow like a bubble but did not break through when tapped on with the butt of a screwdriver. [ATTACH]198718/ATTACH THanks for your help everyone!

Looks like a manufacturing anomaly. Sometimes they will leave a few extras near the HVAC compressor, pool equipment or in the garage in which case you may be able to determine the manufacturer.

Using the SWAG system I would say air bubble MFG defect

Lift up the tile and read the name of the manufacturer on the back. Send them a photo. Recommend evaluation by a manufacturer’s representative to determine the severity of the problem. It appears to be a manufacturing defect, but you’d need to contact the manufacturer to accurately determine whether or not it’s a functional defect.