BPMN contains a multitude of symbols. Therefore, only the basic symbols are displayed in the modeling toolbar. During modeling, only the symbols that are allowed are displayed in a logical order.
Procedure
If multiple symbols are allowed, they are offered for selection. If only one symbol is allowed, it is placed. If no symbol is allowed, an error message is displayed when placing the symbol.
You have placed an object.
If you set a grid, the object symbol will be placed according to the grid width. When you place a horizontal pool or a horizontal lane, the Name attribute is automatically rotated and displayed vertically. If you place objects on pools or lanes, relationships are created automatically. In order to display these, enable the Relationships tab in the Properties bar.