VelbusLink and module status

I’m using VelbusLink since a long time (v6 then v7 and now v8.7).
Why modules are drawn OK but when connected (through Ethernet), each module has a red cross ?
I can read/write without problem on them, so it’s not a problem but a strange display (looks like an inversion).

Could you confirm ?

The red cross overlay is shown to indicate that the module has not been detected yet by a scan since you last connected. So scanning will make the crosses disappear, if all modules are still present.

A scan is the only way to be 100% certain that all your modules are present and accounted for. Being able to read the memory is not a good test, since this will almost always work even if you replaced the module by a module of a different type and/or build.