I have faced the exact same problem. Local Apple store replaced the device. The same exact problem continues. Plus in the last 48 hours I have had two much more significant problems.
(1) When I made a call to one of my contacts, I could not hear anything from the other person. I tried the speaker mode and then I could hear them. Tried to take off the speaker mode, again the same problem. So, I called a second contact with the same results. Powering the device down and powering it back up helped. My view is that if the latest and greatest can’t do the fundamental function I have no use for iPhone X.
(2) This morning while responding to an email the screen froze and there was a line from left side of the screen to about middle of the screen and couldn’t complete the task. Had to power it down and back up again.
I am seriously considering downgrading to a 8 or a 7. This is most frustrating.