Importing Collada DAE , resulted in all objects scaled 0 (zero).
Despite the 0 scale, the data had “correct” dimensions, meaning their true dimensions from Rhino and what would be their correct dimensions in Blender (unit=meters). The scale was not a very small number that would show if I clicked on the scale ! it was true zero ! Consistent with that was if you changed the scale to 1 and applied the dimensions would remain the same.
If instead you tried to selected one or several and scale them the scale would remain 0 because 0x any factor is still 0.
The paradox that saved the day is that the objects appeared as if the scale were 1, immediately when imported. However if you went into edit mode and back out to object mode they disappeared from the 3d View completely and only remained in the outliner, but now their dimensions had also changed to 0 and it was impossible to get the geometry back, to show. Editing a few sometimes resulted in all the remaining changing to 0 dimensions and disappearing for ever.
- Immediately after import, add an empty (at default scale=1)
- Select all imported objects from the outliner (easier if you had imported them all in one collection, by selecting the collection hierarchy objects)
- Parent them all to the empty, tick keep object transformation
- Un-parent them all, keep objects transformation
Result is all objects scaled 1 with true dimensions and same original location…