The pump may be unavailable to remove incoming wastewater. Someone using another connected basin or shower can disrupt the process or cause accumulation.
What the observation means
A toilet notice alone may not cover every inlet. The people responsible need to understand the complete known connection arrangement.
A useful next step
Follow the exact maintenance instructions and prevent all connected use for the stated period. Do not shorten the process by switching power repeatedly. If the required isolation or fixture control cannot be achieved safely, arrange appropriate assistance rather than improvising the treatment.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.