CraftBukkit complains about uncancelled tasks during a reload. Disable cancels task but also sets the PluginMetrics to opt-out globally.

[iain-davis]

I and other plugin others mistakenly thought that "disable" merely shuts down the plugin temporarily (e.g. housekeeping such as cancelling the scheduler task) but it also sets the global opt-out configuration to "opt out", which is not the intended effect!