Cannot Expand any Collections

I’m not sure what happened, probably some setting I did that broke the function, but now whenever I left click a collection arrow it won’t expand, and the cursor becomes a 4-way arrow that doesn’t seem to do anything

Clicking any other mouse buttons doesn’t work on it either. I can still select tools & menus etc with the left button, and also drag to select objects etc, but I can’t seem to access the items in the collection pane

Also, when I open a project, i can left click the drives to navigate in the left pane, but left clicking doesn’t select or open anything in the main window displaying the drive contents etc. I have to use the keyboard arrows to navigate.

Any Ideas?

UPDATE:

I found the setting, for anyone else with this problem, I had accidentally set the Keymap > View2D > Pan View to Left Mouse, where it was default as Middle Mouse. Changing that back to Middle fixed it.

I think it’s very strange that should break the Outliner.