What I have come to understand is that the old OFDM components would output M-ary signals, which should be discrete levels e.g. -3 -1 1 3. However, the M-ary signals that come out of the OFDM component have more of an electrical signal nature, so something is clearly wrong. If you convert these signals to electrical using the M-Ary Pulse Generator and then reconvert them back to M ary signals the QAM Sequence Decoder will function properly. The Subsystem there is for the display of the constellation and the snapshot is attached.