Plan upgrade not fully in effect

I recently upgraded to the Gigabit x2 plan. My device is a Motorola MB8611 DOCSIS 3.1, 32x8. The upload speed should have upgraded from 40mbps to 300mbps, but speed tests show it hard capped at 40 on devices that otherwise get ~1500mbps down. I have tried restarting the modem through the xfinity website as well as leaving it unplugged for half an hour (IP addresses did not change in that time, if that's relevant for troubleshooting). The documentation indicates this modem is capable of more than the 300mbps expected. Do I need a push on the account side? Xfinity Assistant didn't detect anything wrong,