If I use your settings, lower 50 and upper 96, then I have stich errors. My best settings so far are lower 52.5 or 52.25 and upper 95.5. But unfortunately still stich mistakes and I've been working days on this to get right.
You take 4 around, is that enough? I take six pictures at 60 degrees around @-15 degs. I think there is little difference between the NN3 and NN5, except that the NN5 have longer arms. The Falcon is the same as the fisheye Samyang, they both come from the same factory just a different name.
As you are working at Nodal Nonja UK, would you be so kind to test this with a NN3 RD3L 6-8-10 Rotator with built-in EZ-Leveler II and CP-2.
Problem is solved! The settings you specify 50 lower rail and upper rail 96 are correct. The fault lay in an earlier version of the software. It now works perfectly, panoramas without foundation errors.