I've hit a point where i'm stuck 100% because I don't have the second spell (Cup-A-Spell). I've narrowed it down to when it breaks, but it's still an unfortunate bug. When i'm already fighting at the school, I need to use Cup-A-Spell to progress further, but it's not part of my inventory. The second spell in my inventory is the Sneaky Squeaker (the 3rd one). 

 

After recruiting the kids, I had to check in the quest with Cartman. However, before i did that, I got lost in the forest, got grounded and abducted then woke up the next day. On the way out of the house, I Cartman rushes in and tells me to recruit the goth kids. So while i've recruited the goth kids and gotten in the fight at the school, the "Call the Banners" quest is still active. If I attempt to go to Cartman's house, I can't check in the quest and if I exit, i can't and he asks where i'm going (so I can't get out of the area). It just completely skips over where I learn the 2nd spell. This also prevents me from joining his side when the time comes. I can climb the ladder to the tower, but nothing happens afterwards.

Yes, there seems to be a problem with the second day triggering while still on the first due to getting lost in the forest.  I have yet to read a workaround for it.