A shared part of the system may be involved. That changes the enquiry from one isolated sink or shower waste.
What the observation means
The unit, discharge route and installation need appropriate assessment. A running motor does not prove that the common route is clear.
A useful next step
Stop using all affected fixtures and explain their connections. Do not test them one after another or add simultaneous flows to establish the pattern more firmly. Keep the system out of use where overflow is possible and avoid chemical or mechanical attempts to force drainage.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.