For some reason if you disconnect then relog while a spawner is active near you, that spawner will no longer recognize your presence and deactivate. No idea why this is happening.
A fix for it is to move your character far enough away from the spawner so that it no longer senses you normally (about a chunk or two I figure works) then return to the spawner. It was either that or the teleport I did back to home then trekking back out to the spawner that fixed it.
