Hi Takis,
You're right I should've checked before writing, sorry about that. I thought that maybe there is some simple solution to that problem but apparently not.
It behaves as you've described it. I just went a little deeper into the issue and it appears that with the beam tool Dimension Label shows correct values. In the image below I've applied the same complex profile to beam and column.
Cheers,
Łukasz
Łukasz Pietraszko
ArchiCAD 26 PL, since AC20 | WIN 10 Home
Intel Core i7-7700HQ 2.8 GHz | 16 GB RAM | NVIDIA GeForce GTX 1060 6 GB | 500 GB SSD