On Thursday, July 14, 2016 at 11:45:07 AM UTC-7, Cursitor Doom wrote:

When connected to an external bench power supply at 12V., the board draws
9.3mA. The bench PSU doesn't have any issues powering this board.

When connected to PSU that uses the LM317, however, it draws 3mA and the
voltage across it drops to around 6V.

The LM317 requires an output current of 5 mA or more, to bias it. If you
really ARE only drawing 3 mA, that could be the problem.