This video is pretty self-explanatory. Tried checking out some items that I wanted to buy, but the “Transaction In Progress” screen would never complete. I tried waiting for a couple of minutes for it to complete, but to no avail. Eventually I pressed K just to see if I could kill myself while this was stuck, and that worked too. Doing so allowed me to walk around.
The only way for me to get rid of this was to terminate the Tower Unite process in Task Manager. Thankfully the game didn’t steal any units from me.