First, I think I may have had 18.104.22.168 instead of 4.2, as I later found that version number listed as well and I just downloaded it.
Animation Paper as a program appeared to be working completely fine, so I was able to click on all of the Drawing tools and their settings. When I click my mouse or press my stylus on my tablet to draw a line, no line is drawn. It’s like Animation Paper doesn’t recognize that I’m trying to input a command. I’ve never had this issue in any other drawing software either. I’m also assuming that the Eraser tools and more also have this issue but I couldn’t test the Eraser tool with nothing to erase. I hope this all helps to narrow down where to begin searching.