QMenu indicator style sheet undesired behaviour

[Fareanor]

Hello there,
In one of my projects, I used to define my own application theme (via style sheets).

Everything worked fine except when I tried to set an image for the QMenu::indicator:exclusive:checked state.
In fact, it works fine for the checked item but it generates collateral undesired behaviour over unchecked items.
Indeed, if I define an image for the checked indicator, the unchecked indicators become sunk and I don't understand why (and nothing worked to remove it: removing borders, changing border-style, setting an empty image, setting a not empty image, ... nothing seems to affect this ugly sunken border).

You can find the details (context, screenshots, ...) of the problem in the original question here.

If someone has an idea of how to get rid of it, I would be very grateful.

Thanks in advance for those who will spend some time to help me.

EDIT: After performing additional tests, it seems to be a bug. I reported it on the Qt bug tracker, you can find it here.