Changing variable font origin completely changes weight

Hello, I noticed something very odd.

Designed Semibold weight, as it appears in Glyphs. Axis Location (wght): 600.

Variable Font Origin not changed (=first master is used):

Variable Font Origin changed (second of four master is used):

Any reason why this would happen?

Any axes location or mapping?

Yes. I have Axis Location parameters set in all masters (and instances).

Can you disable them to see if that makes a difference?