Not sure if this is intended behavior or not.
Reproduction steps:
- Place some straight rail.
- Place a stack inserter pointing at the rail (so it could supply an engine) supplied by a chest full of fuel.
- Place an engine where the stack inserter will fuel it.
- Place a long arm inserter across the rail so that it could grab where the stack inserter drops items.
- Wait for the engine to fill.
- Move or pickup the engine
- Observe the long arm inserter does not take items from the stack inserter.
- Delete the rail where the stack inserter would place items.
- Observe the long arm inserter beings taking items from the stack inserter.