Depending on the length of text within a Flowchart part and the width of the part itself, some text elements may be cut off and replaced with ellipses (...). You can temporarily stretch the part to show the full text by clicking on the ellipse (...). You can now edit the text. When you have finished, click elsewhere and the part will shrink back to its original width.
Alternatively, you can manually resize the Call action part by selecting the part, then using the square resizing handles.