InputAxis doesn't update if switch to InputModeUIOnly

Hi everyone.
I have a classic WASD mapped input system for my character (it is an ArchVisCharacter).
I can also switch to InputModeUIOnly clicking right mouse button.
When I’m keeping pressed W (for example) to move forward and i click right mouse button, my character correctly stops moving.
But when i return to InputModeGameOnly, W results to be still pressed and my character starts moving forward!!
shouldn’t axis input be updated every frame? if it is so, why forward axis isn’t set to 0.0, since i’m not pressing W or S?

thank you!

Solved, but maybe there is a UE4 bug.
i return to InputModeGameOnly by clicking on a transparent image widget covering all the screen.
if i do so, i get the issue.
if i use a button widget to do the same task, i get rid of the issue.
i have a little test project that demonstrate what i’m trying to explain; where can i upload it to you?