rb750up reboots when btest upload is done(there is loco poe)

I have rb750up and just one loco powered from it. When I do btest download - everything is fine - but when I put btest upload - loco transmits…the current of loco showed in poe details is more then 1,2A and it reboots…
Why? It cant power loco at full speed?
ros v5.22, routerboard v3.0