Members of group disappear when changing, duplicating or placing type

[e.arendsRMCF7]

Good morning!

Lately I've been troubled by a recurring problem in Revit. I have a Revit model with groups that are supposed to be interchangeable, but often (but not always) when I change the group to another group, by selecting the group -> Properties panel -> changing the type in the drop down menu), many of the elements in the group disappear. They are not hidden, they appear to have been removed from the model altogether. The same happens (sometimes, not always) when I go to Type Properties -> Duplicate Type. Revit duplicates the type, and many of the elements (often walls and doors, I've noticed) are gone.

I've attached a screenshot of 2 groups. They should be exactly the same, except for being mirrored.

Has anyone else encountered this problem, and have a way to prevent this from happening?

[Ilic.Andrej]

Mirrored groups are buggy. I would suggest not to mirror the group and then duplicate the type. Instead of that, duplicate the tipe first, open the group and mirror all elements that are inside it.

[e.arendsRMCF7]

Thank you for your reply!

It is good to know not to mirror groups, I didn't know that was buggy.

Sadly, this doesn't just occur when I mirror a group. In this case I un-grouped, mirrored, and grouped again to create the mirrored version. The top one is simply a copy of the previous group, nothing else has been changed. I can't show the group I copied, because when I place the group again, it looks the same as the one already in the screenshot.