It looks like you have a situation where 3 walls are trying to join with each other.
Only 2 can trim properly.
The 2 external walls with the cladding should be the ones trimming.
Each wall has a 'Junction Order' in its settings (or info box).
Try making the horizontal internal wall have a lower junction order than the others.
That should force the two external walls to trim.
Or if that doesn't work you can try to reposition the wall reference lines.
Also what version of Archicad are you using?
To me it looks like a version 15 or older or you have the 'Legacy' option turned on to make it behave like an old version.
It looks to me as if the walls are mitring at the corner - which they only did in old versions.
They should overlap based on building material strengths of each composite skin.
Barry.
One of the forum moderators.
Versions 6.5 to 27
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