Note it'd be nice to specify what part of the UI you're referring to when it might matter, since hit chance can generally appear in no less than three separate places on the interface and you had just written about the Scan window so I was thinking it might be that after not seeing it have anything to do with the robot popup (which is what I was waiting and watching repeatedly for at first xD). Only after a while did I realize you probably meant the weapon-specific hit chance (I don't use that one myself except to see recoil mods).
Anyway, that is fine, it's just a lagging indicator since UI elements can be created and then responsibility for more detailed calculations regarding whether it wants to continue to exist are its own responsibility, but that doesn't always happen immediately. You've seen it elsewhere as well.