I hope this is the right forum for this thread...
If I use a keyboard key to toggle the inventory open/closed there is no problem everything works as expected.
As soon as I assign a mouse button to inventory though (any mouse button) I can open the inventory fine, but a second push of the mouse button doesn't close the inventory as it should (I have to press esc to close it).
Has anyone else seen this? Have a solution, or even just an idea about it?