Some questions for you.
What version of Archicad are you using?
Where are the wall reference lines?
Are the walls all the same top and base heights?
Are there any other walls in other hidden layers?
Have you tried selecting both of the cavity walls and then using the 'Intersect' tool to join the corner?
What happens if you stretch the end of the single leaf internal wall away from the cavity walls - do the cavity wall then join correctly?
If so then stretch it back and see what happens.
Barry
One of the forum moderators.
Versions 6.5 to 27
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