I receive the following warnings on designs that have RAM16X4S and RAM32X4S instantiations:
WARNING:NgdBuild: 452 - logical net 'N_O32X4S<2>' has no driver
WARNING:NgdBuild: 452 - logical net 'INST_RAM32X4S/D4' has no driver
WARNING:NgdBuild: 454 - logical net 'INST_RAM32X4S/O4' has no load
The above warnings are mysterious, as there is no net called N_O32X4S<2> in the design, and the RAM32X4S does not have D4 or O4 pins.
This warning is to help you know if this net or signal was supposed to be connected in the design.