[Code vs Zombies] % character in code causes "Network error: status undefined"

Edit: This turned out to be extension related. Disabled last pass and it works fine now.

Trying to start the Code vs Zombies challenge in Java and I noticed that the inclusion of the % character regardless of how it is used (even just in a comment) results in a failure to run the test case with a little pop-op that says “Network error: status unknown”.

Removing the % character causes the test case to run normally. I also tried disabling the external editor setting and both related Codingame Chrome plugins with the same result.