Why does the box select tool change to the cursor tool when clicking in a blank space? When I click on nothing with the select box tool selected, it simply goes to cursor tool rather than deselect. And when I left click drag with the select box tool selected it moves the cursor tool, rather than making a box selection.
https://www.dropbox.com/s/8gz5srken7omaly/V%C3%ADdeo%2028-02-2020%2021%2037%2007.mov?dl=0

here is a video showing what's going on. 
I already asked on reddit but nobody knew how to fix it.
I have had the same problem, I think it's a bug, but I couldn't reproduce the steps of how to trigger it.

I just created a new scene and appended my stuff from the faulty file into it, that seemed to work as a workaround.