It's not just pressure plates or buttons, either. It's any redstone update that's fed into the command block. Sometimes it will reset before the chunk is unloaded, but 40-50% of the time it doesn't and it gets stuck. I'm currently using BUD switches to get around this, but it's still annoying and should be fixed.
Edit: My suggestion is just to have it keep the chunks in memory for an extra redstone tick or two.
I can confirm this as an issue in 1.4.3
It's not just pressure plates or buttons, either. It's any redstone update that's fed into the command block. Sometimes it will reset before the chunk is unloaded, but 40-50% of the time it doesn't and it gets stuck. I'm currently using BUD switches to get around this, but it's still annoying and should be fixed.
Edit: My suggestion is just to have it keep the chunks in memory for an extra redstone tick or two.