Bug: Timed boxes turn invisible if purple switch is pressed while a different purple switch is running out

[Stevoisiak]

If a purple switch is pressed to make timed boxes visible, then a second purple switch is pressed just as the first switch runs out, sometimes the timed boxes will become invisible.

Steps to reproduce:

1. Create a new level
2. Place timed boxes
3. Place two purple switches.
4. Test level
5. Press purple switch.
6. As purple switch is running out and timed boxes are flashing, press the other purple switch.

Video:
https://youtu.be/ZpqzmAEnSYg