AirPods 2 case isn’t showing it’s charging

i bought an AirPods 2 wireless charging case to replace the original AirPods non wireless charging case. (So I’m still using AirPod 1 buds). When I open the case they appear just fine but if I plug the case in, or put it on the charging pad it doesn’t show it’s charging. The little lightning symbol never pops up! Putting the AirPods in the original non wireless charging case and plugging them in, they show the case is charging just fine. I’ve tried multiple charging pads, cables, and even different AirPods in the case. The little lightning bolts never show up when it’s charging! I can’t tell if they actually charge or not because the case gets warm but upon opening the case after leaving them on the charger, the percentage has gone up slightly but it still bothers me because I never know if they’re actually charging on the pad.