LG Phone - Cannot Charge, Question mark aside battery icon.

[AC Question]

I am unable to charge my LGL34C phone. When I plug in the phone to a microUSB cable, a battery icon pops up in the center of the screen with a triangular '?' symbol to the bottom-left of the icon. Ive tried doing a full drain of the battery, and I know it's not the cable (Ive tested it on another phone). This is my secondary phone, so Im not too worried about it, but it would be nice to have it fixed.