there is something strange going on w/ Sessions and the "war on weed"; Trump didn't promise it, nobody wanted except parts of the LE community, part of Trump's voter base (disaffected BernieBros, and libertarians/ancaps who thought they might strike a blow against the 2-party system) were outraged.

there was little reason to move on it (except maybe as a point to go after MS13 & other gangs, which I think is unlikely)

I have not looked into the following theory at all, saw it over at Ace of Spades by a commenter, so I don't know if any of the points are valid:
Sessions is not going after weed users, as he is in establishing rule-of-law. In other words, states that legalize weed are good b/c it was done by the legal process. cities that played technicalities or made themselves "sanctuary" for weed may be the target. This may actually be aimed at democrat party pols.

IDK, I haven't and wont look at these claims...but it is strange to waste time on weed; maybe the stronger argument is that Sessions is giving those parts of the LE community(pro-drug war) what they want.