LB1111 POE not working

Hi

I am just testing an old LB1111 4G LTE modem/router. It works just fine in either bridge or router mode off the mains supplied 12v power supply. However I want to get it working with POE which the spec sheet says it supports. I've tried a mains POE injector and a ubiquiti aircube and neither could power the modem on. H/W 1.0(0114) Firmware NTG(X25G_02.22.30.04  Build date: 08/12/16

What could be wrong? Can it be fixed? Thanks