- Lot's of bot available (only one used for others things)
- Standing next to a buffer chest with 50 blue UG belt (have only 31)
---> Nothing happens. (if i blueprint concrete on floor, then construction bots will get concrete from buffer chest)

Tried to replace roboports, didn't changed anything, same for replacing buffer chest
History of versions :
16.7 -> 16.12 -> 16.13
No mods