DIAGNOSIS This is usually a safety sensor issue, but not yours—it's the opener's own infrared sensors. The myQ hub won't send a close command if the opener itself reports its safety beams are blocked or misaligned, even if the wall button still works.
FIX Check the main garage door opener's infrared safety sensors, the little plastic eyes near the floor on either side of the door. Make sure nothing is blocking them and that the green LED on one (usually the sending side) and the amber/red LED on the other are both solid, not blinking. If they're blinking, they're out of alignment. Adjust the brackets until both lights are solid.
IF THAT DIDN'T WORK Some older opener models have a compatibility quirk. Try adjusting the "close force" and "travel limit" settings on the opener motor unit itself per . If the close force is set too low, the opener might ignore the remote signal from the myQ hub.
HEADS UP The myQ app has a setting called "Close Confirmation" that requires the door sensor to confirm it's fully closed. If your door sensor is flaky (see other question), this will cause close commands to fail. You can turn this off in the app's door settings, but it's a safety feature.