Not all decimal places are shown on pause menu [1.12.2 at least]
v. 11.4
When less than 3 decimal places are set to be shown, when the run is completed or the game is paused, the same amount of decimal places are shown, not all 3. All decimal places are shown when paused in 1.8.9 and 1.16.1, those are the only other versions I tested.

Can you tell me about mods that you are using?
Everything from modcheck, so: atum, zbufferfog, srigt, tabfocus, sleepbg, and standardsettings
Can't reproduce, must have been a one time bug
this seems to happen for the first launch of any instance, not all digits are shown if global setting is for not 3