Blocking does not prevent you from seeing posts or notes made by the blocked member. Blocking only prevents them from challenging you, leaving notes on your profile, or from posting in forums you create. There are couple of other things too but blocking does not hide their content. It worked the same way in v2 and has still always worked that way in v3 as far as I'm aware.
https://support.chess.com/customer/en/portal/articles/1444796-how-can-i-block-another-user-
I didn't have this problem until recently. I thought maybe a change to the V3 may have undid the change or somehow omitted the cheating forum from the regular forum.