One thing we have discovered/realized since tagging 8.0 is that the grid tool will misbehave if you do "wild dragging" with it between existing tempo markers. I

One thing we have discovered/realized since tagging 8.0 is that the grid tool will misbehave if you do "wild dragging" with it between existing tempo markers. It is intended to "tweak" the grid in that situation, and is designed around small, "subtle" mouse movement. We may be able to come up with some fixes that make it more robust in the face of users deliberately or accidentally going "wild" with the mouse.