All the Tiberian manuscripts (and here, here, here, and here) and the majority of the other (Ashkenazi/Sephardi) old manuscripts* have a maqef, followed by the Venice Mikraot Gedolot and other historically important printed editions.
The testimony to no maqef consists of a handful of old Ashkenazi manuscripts*, followed by some printed editions in the last ...
The source in Soferim you cited says there were three scrolls with only one word different in each. That means the rest was the same.
And you can't just say "Many sources say" and then provide no sources to back up that claim.