ID meshes creation during export

Hello, I’ve faced an issue exporting .DAE files from Sketchup.

I exported .dae file from 3ds max. this is a single model socket. dae file is being exported correctly as a single mesh (checked it both in 3ds Max and Maya).

.dae is being imported correctly into Sketchup. It also keeps the model as a single mesh.

I don’t do any operations with this socket in Sketchup, only need to place it on existing wall in Sketchup and export it as .DAE again.

However when I export the socket from Sketchup as .DAE, and check this .DAE in Unity/3dsMax/Maya I can see that some socket parts were detached from the model, and named ID

Here you can see a video showing my process and issue - Google Drive

Do you know what is the reason for such detachment? And how can it be fixed?
when I export Collada directly from .3ds max, the model stays single and no any geometry detachments appear.
Unfortunately, I need to export the socket correctly right from Sketchup. Will appreciate your ideas.