Issue with Constellation in OFDM Scheme

Good afternoon, I have been trying for weeks to use the transmitter and receiver available at the free repository of gnuradio-digitals. I took the hierarchical blocks of Transmitter and Receiver in their extended form. Utilizing Carrier Allocator, FFT and OFDM Cyclic Prefixer for the Tx, for example.

I managed to get it to work, but the constellation is not what I was expecting, they were locked points for the payload in QPSK. After some digging, I found out about the soft equalizer which helped but the points are way off now. Sometimes they do circle around the place they should be, but then they go crazy.

I wanted some help to figure out this behavior, why is it happening? My goal is to show the offset correction and the points on the constellation should be closer to the QPSK ideal points when the noise is low.

I attached to this e-mail my flowgraph and two pictures of the payload constellation. One is kinda ok and the other is the issue I talked about.