After commit 2d8ab114d866608c11fe427783847d49f07ee435 in xfce4-settings.git#master, the existing dual-head configuration had to be redone. It would be nice if during upgrade from one release to another the settings are imported, if no profiles are found. This is on openSUSE Leap 15.0 with all packages coming from xfce*.git#master, on a laptop with "Intel Corporation Skylake GT2 [HD Graphics 520] (rev 07)" and external monitor via HDMI.
Could you do a little more testing to see which is the offending commit? That would help tremendously in trying to figure out what's going on... Right now I can't reproduce your problem.
You mean a fresh install from last XFCE release, which is upgraded to git#master, will preserve the dual-head config even if that old config did not have any profiles?
Yes, the only functional change on git master is that it first checks if there are matching profiles and applies those. Purging your profiles may also help resolving the issue. But as I said, going through the commits and testing which one leads to the behaviour you mention would be helpful!
I will see how it behaves when upgrading from 4.12 packages to packages from master branches.
This may be a duplicate of https://bugzilla.xfce.org/show_bug.cgi?id=15437 Please try disabling the "auto enable profiles" option explicitly.
This should be fixed meanwhile (with 4.14.1). Please re-open if you can still reproduce.