I also have this problem. I get sound for about a second, then silence, so I know the microphone works. The visitor can hear me but I cannot hear them. I experimented by turning off Bluetooth, but even holding the phone up to my ear, could hear nothing. I have a good Wi-Fi signal (the router is right on the other side of the wall from the doorbell) and the video is perfect, just no sound. Without this working the doorbell is almost useless as I cannot have a two-waya conversation. With so many people having the same problem with different hardware (iPhones, Android) it is not the phone's fault. Ring Support need to fix this problem.
I have the same on a Doorbell 3 plus. I find that I get audio for approx 11-12 seconds then it cuts out. Seems firmware rather than hardware.
Edit: Should have said a hard reboot fixes it (for now).
I am also having this same problem. Wifi is super strong (mesh network with a mesh device very close to front door location of ring doorbell). People at the door can hear me but I can't hear them. My phone is not connected to any bluetooth audio devices. Ring: Please provide a solution!
I'm also having this problem with a Video Doorbell 3 Plus paired with a Samsung Galaxy S8+ running Android 9, and newer Galaxy S20-5G. From App to doorbell, audio works fine. From doorbell to phone app, absolutely nothing. RSSI under device health shows -58, and is green. Ubitquity AP-AC-PRO access point also showing -58. It has a "wifi experience" index of 99 out of 100.
Power cycling the doorbell via pulling the battery is an immediate fix.
Unit bought new Aug 2020. I've got Protect Plan Plus. No issues with Ring Indoor Cam on same phones.
Can you please address this issue?