I think it's a bug because
1. Path to compiler for me is Steam\steamapps\common\App Game Kit 2\Tier 1\Compiler
2. Deleted the AppGameKit and redownloaded because maybe I thought I magically deleted something under the Compiler. It worked briefly but the same error is appearing again.
Causes?
1. I broadcasted it multiple times and it stopped working after that.
If someone else is aware of this bug, please spread the word. If no one else is experiencing this issue, I will try to look for solutions myself. It worked perfectly couple days ago but it just suddenly stopped working.