Okay, so this update to my ProCaptcha plugin will fix the fly issue.

What the issue was:

When a player was in fly it would glitch them out and make it so they could not do the Captcha.

How did I fix the issue:

The way I fixed this issue is so when a player is in the air it will spawn a bedrock block under there feet then after they complete the Captcha it will remove the bedrock block. This should fix the fly issue where it's not registering the player standing on a block.