The committee did not nominate such blockbusters as Drake's Scorpion and the Black Panther soundtrack, both of which wound up with album of the year noms.
The many other noteworthy rap albums that were passed over for best rap album nominations include J. Cole's KOD, Eminem's Kamikaze, Juice WRLD's Goodbye & Good Riddance, Kids See Ghosts' eponymous album, Lil Wayne's Tha Carter V, Nicki Minaj's Queen, Nas' Nasir, Kanye West's Ye and XXXTentacion's ?.
Hussle wasn't nominated in any other categories, though Victory Lap's "Last Time That I Checc'd (featuring YG) was submitted for best rap performance and best rap song. (Miller and Pusha T were also not nominated in any other categories.)
Starting in the mid-1990s, the Recording Academy instituted nominations review committees to counter the tendency of rank-and-file voters to pick the same brand-name artists every year, even if their latest albums are less worthy than their past triumphs. In addition to rap, the other fields that have nominations review committees are American roots, children's, classical, contemporary instrumental, country, dance/electronic, gospel/contemporary Christian music, jazz, Latin, music video/film, new age, R&B, rock and world music.
These committees operate similarly to the separate nominations review committee that determines the final noms in the Big Four categories—album, record and song of the year and best new artist. The committees work from lists of the top 20 or so vote-getters from first-round voting and select the five they think are most worthy. These become the final nominees. The voting membership then selects the winners.
It's possible that Victory Lap was in the top five on the initial list of rap albums, as selected by rank-and-file members, but it seems likely that it was lower in the top 20, and that the committee, impressed by Hussle's talent and promise, elevated the album into the top five.
The academy doesn't reveal what albums made the top 20 on the voters' initial list—in this or any other field. We can only speculate based on other factors, such as the artist's other Grammy nominations and the album's overall commercial and/or critical standing.