Group Challenges freeze sometimes

[Janus]

I've noticed since the game went public on Kongregate (whether that's related or not), when you have a group challenge, sometimes when the last person joins, the challenge goes to initiate, but freezes for about 3 seconds. Then when it loads, you can complete it fine, but it appears as though not everyone made it into the challenge. Is this a bug with them or me? Is it just a display issue or what?

I haven't got any video of it happening, because it seems to happen randomly.

Best I can do is a screenshot showing a group challenge which, when it loaded up, had those participants in it:
http://gyazo.com/675746c7ca7f4309acda6dd81ccd5ede

So missing a person. Sometimes 2 are missing.

When this happens, I can complete the challenge fine, but I have to click "Quit Now" at the end, as it doesn't automatically exit out.

So, is this a problem with me, or a bug/issue?

Let me know what other information I can provide. Thanks!