Description
Bus lines cannot exceed 256 bits due to a simulator Netlist File/SRAM Object File (.snf/.scf)
restriction. However, in your design file, the bus width can be greater than 256 bits. When it is compiled, the bus line is stored as separate bits in the snf.
In the waveform editor, buses of greater than 256 bits cannot be simulated as a group.As such, the "Enter Group" option is grayed out after 256 bits.