Custom sidebar block is caching even though I told it not to

[Louis C]

On my website I have a custom sidebar block that shows the status, channels and users in my TeamSpeak 3 server.

It seems to not refresh unless I press Cmd + Shift + R (using Google Chrome on a Mac) to force a page refresh.
For example, I might load my site, it'll show 2 people in TeamSpeak and then 2 hours later I know they've left TeamSpeak and I open my website and it still shows them there but they disappear when I force the page to reload.

When I created the custom block in AdminCP I left the caching option turned off for that block.
The re-cache time for other sidebar blocks (recent topics, forum stats, etc.) is set to one minute.

Any ideas how I can stop it from being cached and require it to reload?