Full build did not make a difference. To generate the problem:
1) create new empty project
2) set in and out pointers
3) use "attach effect" on the track (right mouse button) to bring up menu and choose a plugin and press OK
You can tell it "thinks" it attached the effect because the patchbay gets bigger but you see nothing.
Do the same thing but instead of using in and out points, swipe a section which highlights that area and do 1-3, it works.
But it does seem like the patch may be better even though I have no idea.
BTW: removing the switches from the x265_3.5.patch3 make lines speeds up the compile so now it only takes twice as long to do a full build -- much better so I checked that change into GIT too.