Sessions has recused himself of all things Hillary so he can not investigate. That call falls on Deputy AG Rosenstein and Rosenstein appears to be, like Mueller, a deep state Hillary fan boy.
Without defending Sessions too much, there are indications that some of Sessions’ recusals are due to him being a witness having relevant information. Even if that were true, at this point he should resign and state the real reason why.
Note that Sessions has said he has not been interviewed by Mueller’s team, but he hasn’t said he has not been interviewed by anyone.
All things Hillary? I thought it was just all things Russian?