Cannot Select Measure (Typical click and blue box should appear answers are not working).

I just starting using Musescore and am trying to select a measure to delete it, and no matter what I try I can't get the blue box to appear.

I'm using Musescore 2.0 on a Windows (10 I think).
- Nothing happens when I left click a single measure.
- When I right click a measure a little menu pops up with the option "delete measure", but when I press the button nothing happens.
- When I try to select a section by clicking a note, then press/holding Shift and clicking a note at the end of the section, nothing happens. It's as if my shift button doesn't work for this function in Musescore at all, though I've used it to select sections for other programs on my computer (such as selecting a group of pictures).
- My Ctrl button seems to work because I can select multiple notes using it.
- If I hold Shift then drag the mouse over a few sections, a blue box appears but disappears as soon as I let go.

No matter what I try I cannot select a section/measure.

Any suggestions? Thanks!