Machines stop working after some time

[Fi0x]

Describe the bug
The mana generator and mana furnace stop after some time.

To Reproduce
Steps to reproduce the behavior:

1. Link a mana furnace and generator together
2. Place items in both of them
3. Let the mana bar fill up in both of them
4. Wait for them to stop working

Expected behavior
It should be possible to automate them without reloading or anything similar

Additional context
Might be a problem with overflowing mana-capacity in the machines