Most likely, the switch for the centerstand is stuck in the depressed position, a relatively common situation. The centerstand switch, which is exposed to road debris underneath the bike, often accumulates grime and periodically needs to be cleaned. The centerstand switch's purpose is to prevent damage to the CVT when the bike is on the centerstand, and thereby has no rotational resistance. When the centerstand switch is "stuck", the ECU thinks the bike is still on the centerstand and prevents the CVT from shifting up to a higher gear.
To fix: With the bike on the side stand, get down on the right side and look for a metal plunger facing the rear. Make sure it is fully extended. Routinely clean this plunger to prevent it from being stuck closed, especially if you drive on gravel or dirt.