Having some problem with FlowDecision in my test ladscape also. Try the attached XAML.
No idea how I achieved it 
By deleting/adding the FD it starts working as expected…
Flowchart.xaml (6.7 KB)
Cheers
P.S. After “Auto arrange” there apeared small triangle not visible before. It is probably an orphan connection causing this problem…
P.P.S It seems to be actually a connection from FD to itself, occupying the “True” connection. I suppose connection to itself should be prohibited.