At least Reviewer status is needed to view drafts.
diff --git a/project.config b/project.config
index b8cc30c..cb08f23 100644
--- a/project.config
+++ b/project.config
@@ -13,6 +13,7 @@
 [access "refs/*"]
 	read = group Administrators
 	read = group Anonymous Users
+	viewDrafts = group Reviewers
 [access "refs/for/refs/*"]
 	push = group Registered Users
 	pushMerge = group Registered Users