When I set max usb current in the maxplay web interface and click Save, the page refreshed but the check box isn’t checked. Is the maxusbcurrent set properly? How to check? Should the line be saved in config.txt, because it isn’t?
Have you rebooted the device afterwards and checked whether its saved now? Also if you have not yet, please update Max2Play to the newest version. I just tested it with a new image and it worked fine.