Nancy Pelosi's strategy of conserving political capital while passing the #forthepeople agenda is being put to the test. At the end of the day, that's what Pelosi's approach is about. It isn't whether Trump is deserving of impeachment or whether any major fact finding mission is required to commence impeachment hearings or to vote out impeachment articles. It's that Pelosi isn't going to invest any political capital in something she believes is relatively unpopular when she can invest capital in things that are popular (e.g. health care).
The equality bill and their ACA fix bill passed the House. They have a few others on tap. Not a one of these moves will see the light of day in the Senate. Yet, she justifies it b/c it will allow her members to tell their constituents that they got stuff done.
The same logic also applies to impeachment btw, and provides a much more tangible result in terms of checking Trump and the Administration, whereas the only tangible legislative accomplishment Dems can achieve is to stop bad GOP bills. They won't pass any of their ideas into law.
For Pelosi's strategy to really work, you have to aggressively use the opportunities to enforce oversight responsibilities where possible. Going after Mnuchin is one of the easier things to do b/c the law is crystal clear. This would be a time to make a move like arresting him and forcing Mnuchin to go to court to stop it. This gentlemanly process of going to court just wastes time and makes Dems look weak.
The other problem here is by relying wholly on the courts, the Dems are taking a risk that a bad fait conservative judge won't accept any of Trump's radical legal arguments, the effect of which would enshrine into law an Imperial Presidency and cut Congress' power off. After all, we're facing down a bad faith law suit against the ACA which was initially supported by a bad faith conservative judge.
While few will defy Pelosi, there isn't unity in the caucus on this. People in the caucus want more aggressive action.