I have seen the director’s cut twice, which I own on Blu-Ray.

I did not say that the film ignores the previous film, I said that it writes it off, which it does. Riddick is depicted as being tired of his role as Lord Marshal and makes a deal with Vaako so he can leave and find Furya. The men who go with him betray him which is how he ends up stuck and the actual plot of the film begins.

Riddick only returns to the Necromongers, finding Vaako missing, to get revenge for his betrayal.

The fact is that the Chronicles of Riddick’s ending is not followed up upon by the main story of its sequel. He is set back to square one - being stranded on a desert planet. It’s not about Richard B. Riddick, Lord Marshal of the Necromongers, it’s not about Riddick finding Furya or dealing with anything that came up in the second film. It’s an almost entirely disconnected sidequest that came about as a result of the film’s reduced budget.