I have two base glyphs and a mark. Let’s call them B1, B2, and M1.
Ignore the spaces and let’s say I type B1 M1
The mark goes into perfect position.
Then I add B2. So we have B1 M1 B2. Now B2 kerns -100 to B1. But here, not only that kerning happens but M also gets shifted back by 100.
If I use another mark, let’s call it M2, then if I write:
B1 M1 M2 B2
then B2 kerns properly but both M1 and M2 also get shifted back (kerned).
Oh, I updated to the cutting edge version and the rules for the anchors are different! I never was able to get the rules for the older version’s anchors. But had most of my anchors working by one by one trial and error. Not anymore, some no longer work with this cutting edge update, and so far no luck in working out their new rules. It would be very very helpful if anyone could explain what rules the anchors function with! I made a thread about it here but no indication of the rules yet: