There is likely something conflicting with this spawner. Do you have another Spawner enabled? If so you should disable any other Spawner.
If the event requires you to erase the event manually on unspawn then something is causing the unspawnEvent function to not run properly which would result in improper spawner data which could cause problems such as inability to recycle events properly. The Spawners Data Objects would not be updated when events are unspawned if that function isn't running properly. It's probably best to find the cause behind the issue rather than finding a workaround.