LabVIEW (2019 was used here) displays a dubious behaviour when you change a text control to "Update value while typing"; If the control display mode was Hex - LabVIEW allows itself to silently add a change of the display mode to "Normal". 😲
Others here have commented on the lack of support for "Update value while typing" when in hex display mode (which understandably poses a bit of a challenge, but could have been implemented by updating on mid-stages as well), but this automatic silent side-effect is a bit nasty as it is very easily overlooked. It would be safer to either disable the Update value while typing option while in Hex Display - or show a dialog asking for which supported display mode to change to due to the inability to support the given combination.