Ok, so after a bit more investigation, in case anyone is interested, it seems like this is 'layout' related. Some time ago I accidentally pressed some hotkey which changed the layout, such that the orders go at the right at the bottom of the screen, instead of the left. I didn't know how to change it back, and just left it like that.
In any case, I looked into this and worked out how to cycle back to the standard layout, and the issue I described above now no longer happens.
I guess something in a recent update broke things in the UI in some way, but only when using a non-standard layout..