Hand/Selection tool glitch in pages panel with second monitor

I've encountered a consistent problem using Indesign 14.0.3 (and previous) on Mojave 10.14.6 on MacBook Pro (Retina, 15-inch, Mid 2014).

When a second external monitor is connected, and both monitors are open, the cursor gets stuck between pages in the pages panel. It seems to flutter between the hand and pointer tool and I have to shake the mouse to release it from this position.

When only the external monitor is being used, macbook is closed, there is no problem. I've had this problem consistently on various external monitors, different OS and adobe CC versions.