camera locks unintentional on certain occasions

Dear reader,

For the past 2 weeks I experience a camera related bug. I always play with unlocked camera, but somehow a few times per game it gets locked and I can only unlock it by pressing the camera button next to the minimap. This is ofcourse very annoying.

I use the Mousebutton 4 button to self center instead of the space bar.

Any methods to fix this issue? Or is it a coding issue?