Unable to use a double quote mark (") in the field label (via Application Language index) as it causes forms to stop functioning correctly. Toolbar buttons don’t work, drop-down selection lists don’t work, etc.
Removing the field from the display (via Edit Fields or Field Positioning) allows the form to work. Moving the field back to the display sections breaks the form again.
Example of a problem field label from Application Language index: “What” To Do