periodically, components stop behaving as units, and start behaving like ungrouped objects
after maybe some component deletions, or other routine operations, Sketchup 2020.0.373, will stop treating components as single unit, and start treating them like ungrouped geometry.
the problem is easily fixed by saving, exiting and reopening the same file. everything is back to normal.
this has happened more than once, seems to be a daily occurrence. happens to all components in the file at the same time.