Site Property Line - Strange Effect on Model Line Family

[Batman]

In the images below you can see a bathroom with sinks and shower (family made from symbolic lines); off to the right side of the building is the Site Property Line.

As soon as I switch off the property line vis the plumbing families also disappear.

I've found that they are actually at the same height as the floor level. I move them up above the floor level a very slight amount and they become visible again; no problems. The families were added after the floor was modelled.

BUT....

Why does the property line visibility affect these components?

Another bug....?

[Steve_Stafford]

can you paste these into a blank project and post. Does it do it in the blank project if you do.

[Batman]

When i copy clip them it doesn't do it. Perhaps some corruption in the file.

I have some ADT files included which did some funny things at the time of linking.

Thanks for the advice.