Unexpected behaviour of FollowMe in SU2023

I tried to create a lip by using FollowMe round an arc, with the profile set normal to the midpoint of a segment of the arc:

The Priofile is displaced radially inwards, and I can’t see why.

Lip of pillar box 15 June.skp (202.0 KB)

I can only get it to work as expected by moving the profile to the end of the arc, and rotating it slightly to be normal to the end segment

That works as expected.

Any thoughts about why the first method gives the results it does?

It works the same on @Quadhurst’s computer, also a Mac, also running SU2023

From ‘middle’