Found 2 other bugs:
1. Conveyor belts make water disappear somehow - conveyor belt surrounded by water transports it to the end and then it sometimes vanish - water level can't rise above conveyor (only few blocks can be above before they get transported and destroyed).
2. Connection T1 Pump - Transmitter - many fibers & deflectors - Receiver - Compressor - Materializer; water is normally transfered to Compressor, but it 'sticks' to Materializer - there's one water block sticked to Materializer on output, but no more water is emitted, although it is removed from Compressor. Network is not splitted, and without Materializer it works fine (water is collected). After relaunching game network stops working and water placed manually in Compressor is materialized fine. Network is about 1/3 central flat cube long, if it matters. After walking along it and replacing some random elements it starts working as described above.

If optical fiber is broken while transfering resources, they're still disappearing from source. Is it intentional or bug?