Yes, phone is up-to-date, just verified.
(NOTE: it was very difficult for me to post this reply; the reply button kept showing a red error box. I had to mess with the source HTML to post this reply.)
I just booted into safe mode, and after about 15 minutes I saw it happen. The bottom of the clock digits were covered, as well as everything below on the screen (this includes the battery percentage, the safemode notification icon, and the words "Safe mode" in the lower-left side of the screen). In other words, the only thing that was visible was the top half (approx) of the clock digits. It's like there's a black/opaque GUI element covering the lower portion of the display. It's a perfectly straight horizontal cutoff.
I changed from clock style 4 to style 2 and have not seen this happen again. I guess clock style 4 must be glitched. Its almost like a screen saver started over it or it's somehow going to sleep. Soon as I move the phone it snaps back. But i have seen the clock disappear completely as well. But nothing on style 2.
I switched to one of the analog clocks (number 7 if counting from the left in the list of clock styles). It's been about 12 hours, and I have NOT seen the issue occur. Note: I saw the issue when using clock style 4 (digital, large hour, small minute); I'm not sure what clock styles others are using. I'll try a few different digital styles and report back.
I've had my phone set to use the 1st clock style (from the left) over the weekend, and did NOT notice the issue. @Bryansanders22 confirmed that clock style 2 is ok, so I'm going to try style 3 today and see how it goes. So far only style 4 is confirmed bad.
(NOTE: this website is still misbehaving. if I hit the Reply button, a moment later a red rectangle appears that says "Sorry, unable to complete the action you requested." I'm only able to post replies by right-clicking on Reply, clicking Inspect, and then manually going to the reply link in the source code. Using latest Chrome on Windows 7.)
In the last 24 hours I used the 3rd clock style (from the left), and the 5th, and have NOT seen any issues. I just switched to the 6th one (outline of numbers, hours over minutes), and will see if there are any issues there, but it's looking more and more like this issue is localized to the 4th clock style (digital, large hours to the left, small minutes to the right).
I can at least confirm that it's not specific to clock style 4. I've been using the 3rd-from-the-left clock style, and this bug occured on my phone today. To be clear, I'm suing the style that has this layout:
12:33 Tue, July 23 89%
1) 12:33 was cut in half horizontally, with only the bottom half of the numbers visible. "Tue, July 23" and "89%" were also visible.
2) 12:33 appeared to be near the center of the display at the time.
3) The AOD was disiplaying with high birghtness, even though adaptive brightness was enabled in a dark room, and is normally much dimmer.
4) When I touched the display, the AOD display briefly blanked and then came back.
5) After it came back, everything was back to normal. The time was no longer cut off and the brightness was appropriately dimmed.
One UI: 1.1
Kernel: 4.14.78; #2 Thu May 2 14:59:15 KST 2019
I'm also getting the "Sorry, unable to complete the action you requested." when hitting the Reply button. Chrome on Windows 10, latest versions. Had to inspect the page code to get the reply link.