Error "No Appropriate method, property or field 'backendld' for Class 'SLM3I.Diagram' " while adding if-elsif-else chart pattern

Hello,

As shown in screenshots, when I try to add an if-elsif-else pattern in state flow chart and press "ok" this error is displayed and the wizard doesn't generate the chart icons : Error "No Appropriate method, property or field 'backendld' for Class 'SLM3I.Diagram' "

I've checked all inputs/outputs and conditions and I can't figure out what is wrong.