I see that two Durham students completed dissertations related to Galatians this year. Unfortunately, both of them are under and author-imposed embargos. You can either wait a year or three or head on over to read the abstracts:
Tedder, Samuel John. Children of Laughter and the Re-Creation of Humanity: The Theological Vision and Logic of Paul’s Letter to the Galatians from the Vantage Point of 4:21-5:1. PhD; Durham University, 2017. http://etheses.dur.ac.uk/12219/
Griggs, Lowell Robert. God the Life-Giver: 4 Maccabees, 4 Ezra, and Paul’s Letter to the Galatians in Conversation from the Vantage Point of 4:21-5:1. PhD; Durham University, 2017. http://etheses.dur.ac.uk/12074/