gpio 48 broken on Rev C boards from Element14?

I’ve been using Rev C BeagleBone Black cards for several years. The last couple of batches came from Element14. I run a RobertCNelson Debian 4.4.21-ti-r47 from the SD card. In the last batch of cards, gpio48 does not work. It’s configured as output, but stays at about 0.9V whether its on or off. All other gpio pins that I use as gpio (49, 60, 115, and 117) work fine.

This appears to be specific to the new batch of cards. The same SD card (OS and application software) in any of my older cards works fine. Fails in any of the new cards.

I’ve verified that the /sys/devices/platform/ocp/4804c000.gpio/gpio/gpio48/ files are set correctly - direction and value in particular.

I’ve measured the physical voltage on the actual BBB pin (15) and it does not change. Should be 0 for off and 3.4 for on (it’s connected to an external 10K pulldown) - it measures 0.9V in both cases.

Anything else I should try before sending these back?