The following error message appears when setting up Relations for the LebeledField element :
Internal program error:
In the case of setting up the "Nearest" option, this setting will not be saved.
This is a known issue.
The IPE is shown when the user clicks on the "OK" or "Apply" button after setting up Relations or the "Nearest" option in the LebeledField element Properties->Relations tab.
As a workaround, a combination of StaticText and CharacterString fields can be used instead of LabeledFieled, where the StaticText field is used for the label and the CharacterString field is used for the value:
Also, worth mentioning, it is still possible to use Relations. Because despite receiving the error, in case of clicking on the OK button Relations will stay in place, unlike the Nearest option.