Vivoactive6 is not vibrating on messages

I've been using the Vivoactive 6 for a month now, and everything was great at first. However, in the last few days, my watch hasn't been vibrating when I receive messages on my phone (WhatsApp/Viber/SMS/Mail). The message does appear on the watch under notifications, but there's no vibration.

When I use an app like Google Maps, the watch vibrates to notify me when it's time to turn, which means the issue is not with the hardware — the vibration motor works. The alarm also works fine and wakes me up with vibration. All notifications are enabled, and the apps have all the necessary permissions (on watch and garmin connect app on phone). Any solutions on this problem?