Can't add Corner to extra node

Glyphs
#1

My version is 3.04(3108)
After try many times, but I can’t add the Corner to that extra node. It always add to the adjacent node. It also can’t add to the right position if you add corner to the other adjacent extra nodes. as below shows:

corerbug
corerbug1354×1194 102 KB

cornerbug.glyphs (8.2 KB)
could you help, please.

#2

Could you help find the reason? Thanks a lot.

#3

i faced the same issue. waiting for the right answer.