Homekit: Accessory already added?

Update: I spoke with Apple support for quite awhile and we tried many things and none were working. The support person, Lisa was personable and very knowledgeable. She was aware there had be issues between the two apps. After not finding a resolution she said she would elevate it to engineering and suggested I contact Leviton as well. Then she'd get back with me tomorrow.

Called Leviton and again they were knowledgeable. We did a reset and he suggested I try to add it to Home before adding it back to the Leviton app. Still didn't work but we got a new error. Sorry can't remember what error said. Basically already added. So we reset the switch again, added to Leviton (no problems) and tried the Apple app with the same results. We reset the switch again twice and he also said he would elevate the issue. He also said he would email me about the issue. We left with the switch reset but not added to Leviton. Afterwards I added the switch back to Leviton, again no problems and tried one last time with Homekit. Eureka!! It added!

So no definitive fix was found But both companies are aware of a issue and are working on a fix. Leviton is expected to release a Matter update soon and "maybe" that will be the magic bullet.

I found Lisa @ Apple very helpful and Leviton was too. Both were aware there was a issue and neither blamed the other for the problem.

I am having the same issue with a Leviton D215S v2. It worked flawlessly for over 8 months and then after the latest Home update it went "not responding".

The error says "Accessory Already Added. To add this accessory to your home, you'll need to reset it first"

1. I reset it....same
2. I deleted it and re added it.....same
3. I renamed it.....same
4. I changed its IP....same
5. Scanning or entering the code manually........same.
6. I followed many of the other ideas in the other threads.....same

Thing is it works just fine in the Leviton app. ALL the other items are working fine in the Home except a Schlage lock (whole other issue) sooooo this appears to be an Apple issue!