Blackmail files are extremely powerful. There is the strong possibility that a compromised Republicant Senator or three will be threatened and respond as ordered by whomever hold the files. Amy would be too important an addition at this moment in time for the demon rat masters to allow her to be seated.
The Senate Democrats seemed a little passive last week - too accepting of defeat. Maybe those files are the arrows Nancy still has in her quiver, and some surprise names will vote "No" at the last second, without consulting Mitch.