Delete / remove doesnt do what it should do

It happens often that deleting a record refuses to do what I ask.

Like in the case below. There are no parents, no children. Just an empty record but I can not delete it. There is no explanation why deleting is not allowed.

Sometimes the message “removed 0 records successfully” shows up right-bottom screen after I selected 1 or more records to delete. That is a nonsense message.