I have three lotteries. Each one of them has 8 signs placed around my server, so 24 signs total.

After about two hours of counting, they stopped counting and updating. The /l info is still accurate and counting.

I did an /l config reload, and it updated with information that is about 6 hours old. I did it again and no change.

I'm sure a server restart may fix this but I don't want to interrupt user gameplay and it will likely occur again. Let me know if you need me to do any specific tests.

Indeed, occurred again after a few hours.

Restart fixed it. I will keep an eye on this to see how long it takes to happen again.

I'm not sure what's been causing this bug. I've been very careful about following CraftBukkit's instructions about scheduling tasks to make sure the signs are updating and they still seem to be doing this.

Does it do this randomly or after a drawing or anything?

It happens randomly. No specific action makes it happen. I can't test this specific issue anymore as I've unloaded the plugin until the other report gets fixed (see renamed items issue).

Should be workin in v0.8.6, if not Bukkit's to blame here.