Hello djoneswi,
Thank you for using Apple Support Communities. Sounds like your HomeKit accessories are not properly working. Specifically, you're unable to hear the doorbell chime when people use your Wemo doorbell. It also appears that you've done a great job in troubleshooting this issue. Resetting and restarting all devices as a great approach to try.
If those steps didn't help out, you might want to try to remove those accessories and re-add them to the Home app. This can sometimes help refresh things. To remove the accessories, follow these steps:
1.) Open the Home app
2.) Long press the accessory and select Accessory Details
3.) Scroll down to the bottom and tap on Remove Accessory
Then you can try to re-add your accessory: Add an accessory to the Home app - Apple Support
1.) Open the Home app and tap Add
.
2.) Tap Add Accessory
.
3.) Use the camera on your iPhone or iPad to scan the eight-digit HomeKit code, or QR code on the accessory or accessory documentation. If you have an iPhone 7 or later and see
on your accessory, hold your iPhone near the accessory to add it.
4.) When your accessory appears, tap it. If asked to Add Accessory to Network, tap Allow.
5.) Assign your accessory to a room and name it to help you identify it in the Home app and control it with Siri.
6.) Tap Continue, then tap Done.
We hope these steps are helpful. Thank you for using Apple Support Communities.