Popup "Discovery checks" broken when configuring action conditions

When trying to add "Discovery check" as a new condition to a discovery action, there is an error in the popup where I can should select a discovery check:
Undefined index: dchecks [popup.php:197]
Undefined index: dchecks [popup.php:198]
Critical error. Incorrect value "dcheckid" for "srcfld1" field.
Critical error. Incorrect value "name" for "srcfld2" field.