Hi i'm not sure if qualifies as an idea or somesort of a bug-glitch, or its just my luck of knowledge.
When in sub-object mode the gizmo doesn't follow the mouse movement but jumps to the location when you let the left mouse button go. But when moving whole objects the gizmo does follow.
If its not a bug my suggestion is to add an option that would allow the gizmo to follow subject (lines, vertices, polygons) just like it does when you move whole objects
If it is a bug I think you guess you guess noticed it before, and its probably just so deeply rooted so you cann't easily fix it or maybe its was design that way for some other reason that i don't about (sorry about that then)
Here is a thread with video examples, if explanation isn't clear.
https://forums.autodesk.com/t5/3ds-max-forum/gizmo-doesn-t-quot-follow-quot/td-p/6891950
Best Regards