Label created in an unknown layer

You could use Window->Assistants->Dynamic Selection, and then hover over the label, and it should show you the layer it's on. If when over the label and it's highlighted in the assistant, then you can press ctrl-H and it will freeze the contents of the dynamic selection assistant to allow you to expand it to see the full entry.

Then having identified the layer, you can edit the valid layers in the layer palette and turn on the validity of that layer and then you can select it.

Andrew

Using the Dynamic Selection, the layer is not detected.
But from LVS, it is mentioned.
So I know the name of the layer, but it is not there in the layer pallet.

In my original post, the layout is small. So I decided to copy the layout to a new one without including this problematic label.
Today, this happens again in a bigger layout and I prefer not to do the same trick like before.

Is there any tips that I could try?

Without seeing the data, it's very hard to know what might be wrong. Dynamic selection should show up everything in the technology file, even if the layers are not "valid". You could change all layers to be valid via the layer palette so that they all show up, but I doubt that's it.

The layer name in the LVS rules is unlikely to be the same as the layer name that Virtuoso uses, by the way (it might be, but it doesn't have to be).

Probably the best approach here is to have a screen-sharing session with customer support so that you can show this to an application engineer to try to debug.

Andrew