Affinity Designer Subtracting shapes

[FrankSSt]

Help please...

Affinity Designer 1.9.0 on Mac BigSur

for the life of me I cannot figure out what is causing the different behavior when subtracting shapes.

the blue triangle is a shape I copied over from an existing document. the green triangle is one I drew myself. the 2 orange circles are copies of each other. 

If I subtract one of the orange circles from the green shape, it does what I expect, it punches a hole into the shape while retaining the stroke.

Doing the same with the blue shape, it adds the hole but fills it blue - and I cannot figure out why it is doing that. It must be some property of the blue shape I am not seeing (or know how to change).

I have attached my sample file and also a screenshot

thanks for watching....

Subtract-issue.afdesign

Edited February 23, 2021 by FrankSSt

[Alfred]

Welcome to the Serif Affinity Forums, @FrankSSt.

Take look at this thread from a couple of hours ago: