Your mileage may vary, depending on... who knows what. This is what works for me, for now.
Step 1. Someone presses the doorbell. This seems to break the ability to talk - in any app that works with the AD110.
Step 2. If you have push notification enabled in SmartHome for the AD110, dismiss the notification. You don't want to answer (that won't work). If you accidentally answer the call, just end it and proceed to the next step.
Step 3. Open SmartHome, open the doorbell live view, tap talk. Talk will fail, but this seems to reset the ability to talk (and be heard) from... Amcrest View Pro.
Step 4. Open Amcrest View Pro*, open the doorbell, tap the speaker icon and then the microphone icon. Wait for the mic to become unmuted. Talk to the person who rang the bell if they're actually still there by then.
*In Amcrest View Pro, for the talk feature to work, the device connection to the AD110 must be a direct connection. You will not be able to talk using a connection through your NVR. You can still view live and playback footage through an NVR connection, but talking won't work.
Until very recently, I used to be able to answer the call successfully from the SmartHome push notification every time, as long as I always performed step 3 after every call to "reset" it. The behavior has suddenly changed and it now appears that the action of the button press itself is what is breaking the talk capability prior to answering the call. Formerly, it appeared to be a successful call-answer that would afterward leave the talk capability broken for the next call.
The only other noticeable thing to have suddenly changed in my implementation is that now my Amazon Echo has begun announcing button presses, whereas before, echo integration was limited to my FireTV. (I could never talk from the FireTV implementation of SmartHome, just as I could never talk from SmartHome iOS app, BTW.) The interaction between SmartHome and a non-view echo is new for me.
My AD-110 is still on the firmware I received it with: 1.000.00AC003.0.R191113
I do not have a memory card installed, and I do not subscribe or use cloud storage.
I do use it with an NVR. I have left the video encoding settings as original after having reset it.
Formerly, it was set to static IP. Since having set a static DHCP assignment in my router (to the same address), I have switched it back to DHCP mode. It still does not appear in my wifi mesh's list of connected clients which is the same behavior as expected for non-DHCP devices, which is odd, but is the least troubling concern I've had with it.
It was the act of configuring motion detection in the Amcrest View Pro desktop app which restored proper motion detection reporting from it after that had been broken by setting the static IP address using my NVR.
I hope this information provides useful for anyone else struggling with the AD110. I feel as though this is a great device, but the SmartHome implementation has added some bugs. I'd love to be the first to try an original Dahua firmware on it and abandon SmartHome altogether, but I'm afraid to brick it in the process.