We checked with Alarm.com, and their recommendation is to unlink and re-link the Alarm.com Smart Home skill in the Alexa app. This will also rediscover your devices. Once that’s done, give your lights a test with Alexa and let us know if you still get the error.
Here’s our guide on linking Alexa with your Alarm.com account if it helps: How To Pair Amazon Alexa with your Alarm.com Account