For example, let's take Clinton tech aide Bryan Pagliano, who was granted some form of immunity by the Justice Department. The timeline on this seems confusing, but I'll summarize information I found:
In March of 2016, Republican senators sought to compel Mr. Pagliano's testimony reportedly indicating that his grant of immunity by the DOJ prohibited him from invoking the Fifth Amendment right against self-incrimination. In May, it was reported that "The [State] Department has searched for Mr. Pagliano’s email pst file and has not located one that covers the time period of Secretary Clinton’s tenure,”
In June 2016, it was reported that Pagliano had filed a motion in seeking to keep the immunity agreement secret in a case involving a Judicial Watch FOIA request. Later that month the judge the document should remain sealed “because the government’s criminal investigation through which Mr. Pagliano received limited immunity is ongoing and confidential.” (Presumably Pagliano's deal was related to the FBI investigation into the private e-mail server he administered for and which Hillary Clinton used instead of official state department servers.)
Later, on September 13 of 2016, the House Oversight and Government Reform Committee voted to send to send a contempt resolution to the full House for Pagliano's refusing to testify in a hearing. (Note: Pagliano's attorney indicated he would take the 5th in open session, but be willing to testify in closed session.) Wikipedia's summary indicates that the full House never considered the resolution.
Can Congressional Committees still compel Mr. Paliano's testimony?
Has this situation been clarified in the subsequent 24+ months?