Unable to use Various Functions on Scratchpad

Hi all,

For some reason, when loading an image as reference onto the scratchpad, I cannot use any functions beyond the freehand paintbrush. This includes the colour picker and the “move layer” function, which I use to reposition my reference to get a better view of a certain area quite often. Any idea why this is? I am currently using Ubuntu 18.04.1 LTS. I know for certain I have used this function before, on other Linux distros, and on windows as well I believe. There are no errors associated with this problem. The program functions normally, and when the cursor is positioned over the scratchpad it switches to a tool as is expected. However, even when selecting the colour picker or move tool or anything else really, it simply reverts to the freehand brush. The only workaround I have right now for changing the area of my reference I am focused on is zooming in and out awkwardly with the scroll wheel. Any help would be appreciated!