I just discovered what I presume is a bug with the adjust command. Searching the forum I see that this might be a recurring bug, although I'm not sure it's the same behaviour.
For me, the adjust commands cuts quite randomly instead of removing the shorter part of the line as it has done before. I haven't been able to figure out any pattern in what side is removed, neither length, number of nodes, line direction nor side selected seems to affect it.
I have no issues with adjusting the polyline to make it longer.
Archicad 24-25 SWE Dell Precision 5560, Windows 10 Pro 11th Gen Intel(R) Core(TM) i9-11950H @ 2.60GHz 2.61 GHz