Doorbell doesn't ring inside, only outside, and also doesn't alert us that anyone is there.

We just noticed that our doorbell isn't ringing inside. We had an electrician show up this morning and he rang the doorbell and we didn't hear anything. My husband said he could hear it faintly but I didn't hear anything. The reason is because he just heard the ringing outside. We also didn't get any notification that there was anyone at the door. I charged it back up to 100%, evn though it was only at about 50%, to see if that made a difference. It didn't. It says both the Front Door and the Hallway (where our Chime Pro is) are fully online. However, when I take the doorbell off it's post by the front door and simply walk inside the front door, maybe 2 feet from where it usually is, it rings inside and we also get notification of it. What is going on and why is this all of a sudden happening when we've had this for over 2 years?