Not all kanban containers have status WAIT

What causes this issue?

You want to delete a control cycle. However, not all kanban containers
are set to the status WAIT in this control cycle.

System Response

This is not possible as kanban containers are still in circulation. For
example, replenishment may have been triggered for empty kanban
containers or material may still be available in full kanban containers.

How to fix this error?

Proceed as follows:
Lock the kanban containers. After the status sequence has been
completed, the system will automatically set these kanban containers to
WAIT and not to EMPTY.
When all kanban containers have the status WAIT, you can delete the
control cycle.
In exceptional situations, you can also set the kanban container status
to WAIT using the kanban correction functions. However, in this case,
you must cancel any replenishments already triggered and you must also
deal with any material still available in the full kanban containers.

Error message extract from SAP system. Copyright SAP SE.