Where did you order ADT-3's? US store is out of stock.I have a friend with a Sabrina dongle. Completely unmodified, and running a pixel 2 xl, also completely unmodified. She's been having crazy trouble with casting and remote control for a few months. I honestly think that this stuff is pretty weakly implemented and unreliable.
Personally, I don't use cast OR remote, since I've decided to degoogle myself completely. GrapheneOS on Pixel 6 Pro is very nice. Best just to install your software on the TV dongle and be done with it. I also have a couple of ADT-3's that are supposed to be delivered today (although its a pretty serious snow storm here today, so might have to wait a bit longer) to replace my Sabrina dongles, since they're basically the same but unlocked from factory. Yes yes, no netcrax -- I don't like them anyway.
The big problem I see with this casting and remote stuff from gooble, is that they've decided to pull an apple and reinvent everything unnecessarily. There are standardized casting technologies that actually work reliably, and a phone can be programmed to be a USBHID device without needing to use undocumented network protocols to accomplish the exact same thing.