Brush editing - Selection (Bug?)

Hi,

I’m very new at creating content in UE, but I m having some troubles creating a plan for an appartment. I already build a wall and expanded it around outer border with brush editing.

After I safed and reopend the project I can still select the part of the border that needs to be extended, but a whole more extends when I do that.

For further explaination:

3 Parts (all 3d)
A, B,C
I want to extend from C on, but it starts from B. Every time.

Does someone knows that problem, and hov to solve it?

I Have UE 5.3.2

Thx, I dont want to start building from the beginning…