"Always One Selected Value" is enabled in a List Box containing a field. If the List Box is removed the "Always One Selected" is still active and if a new List Box is added containing the same field it will by default have that setting active.
"Always One Selected Value" is a field setting. This means that if the setting is added in one List Box it will effect that specific field in all other objects. A field setting will be kept regardless if an object containing that field exist in the document or not.
"Always One Selected Value" can be disabled in the in the List Box properties.
- Right click on a List Box
- Go to General tab
- Deselect "Always One Selected Value"
If it is unknown which fields have "Always One Selected Value" enabled
- Go to Settings > Document Settings > Tables
- Browse through the field list
- Always On in column Type indicates the field has "Always One Selected Value" enabled
- To disable the setting, follow the steps in above paragraph
If there are Hidden Fields
in the document, "Hidden" will be shown instead of "Always On" in the field list.
All the hidden fields should be checked by manually adding those fields as List Boxes and checking their properties.