Ok, I played it again! Overall, the controls work. Maybe I was tired the first time, but I got the caster to work this time. (Last night I kept charging and firing with no result)
As for the thing that felt like a freeze, I figured out what it is. When the enemy attacks the shield girl, if you accidentally click on a random tile instead of "tank" everything "deactivates" and just sits there. If you hit the cancel button, it goes back and the "tank" option reappears. When it happened the first time, i didn't think to hit cancel and it seemed like I couldn't do anything at all, and the enemy was just waiting in place, not attacking. Through accidental clicking I figured it out.