Can't use backspace key when writing tag name

[Lurch]

I’d imagine this is due to the same problem as this;

Backspace not working in custom reports formula box for Firefox

I was playing with the custom reports earlier and did the following. Clicked the ‘show all’ at the side of the nominal code lookup box. Selected 4000:4999 - All Sales. Dragged & dropped this into the formula box. Now I can’t edit or delete the entry in the formula box. Obviously I can delete and recreate this line but I don’t think I should have been able to break it by doing this. Actually, now I have created a new report it seems that I can’t use cursor keys or backspace in the formula b…