Group elements changing height after export and re-link

[_deitch]

We have some elements within a model group that are behaving strangely.

The set-up:

1. Workplane-based families are placed within a model group consisting of walls. Elements are aligned to faces, nothing is hosted to another element.
2. All of these families have default elevation set to 0, and parametric relationships set to reference planes within the family.
3. Model group is exported using "Save As Group" with attached details, then linked into the file and placed throughout the project on different levels.

The result is a handful of these elements offsetting from the reference level by the value of their 'mounting height' parameters. Things I have tried:

1. Edit Group > then select elements, cut to clipboard, and paste aligned to level.
2. Delete mounting height parameters, then create new ones.
3. Re-host witness lines for parameter dimensions.

Still, the problem persists and the only solution has been to open the project, adjust dimensions, then save and reload the link.

[syman2000]

Can you post the group Revit file here so we can test it from our end? I am curious if it is the hosting object that disconnect when they cannot find the workplane or it is something else missing.

[barthbradley · Accepted solution]

https://knowledge.autodesk.com/support/revit-lt/learn-explore/caas/CloudHelp/cloudhelp/2017/ENU/Revi...

...one more thing: do your group contain groups (e.g. nested groups)? Nested groups are problematic and a no-no.  FWIW.  

[_deitch]

Thanks for sending me down the right path! There are no nested groups in here, just nested families. The common thread among these misbehaving families is that they were developed from the same template and have a default elevation from level set to 4'-0". When the group is exported, the "mounting height" family parameter values are written to the offset from host value, so a TP dispenser at 2' appears to be 4' above the workplane. Deleting this parameter and re-writing it didn't help at all, but importing the geometry to new families and then setting them up properly.

I can reproduce the effects in different project files, but I haven't quite nailed down the exact steps the family author took to cause this condition.