I've just discovered that I caused a systemic error in several scripts dealing with Groups in relating the LabelTable.LabelID to the GroupTable.GroupID when the latter is actually related to LabelTable.LabelValue. It's of no consequence when groups are consecutively created but not deleted because the LabelID and LabelValue match. The problem arises when a group before the latest created is deleted; the LabelID for a subsequently created group could point to the wrong or a non-existent GroupID.
Over the next while, I will try to find and correct those scripts. A starting point for identifying them would be a site search using both terms "LabelID" and "GroupID".
UPDATE 2020-05-16: not as bad as I feared. The original error was corrected in many but not all scripts in 2011. Here are the exceptions that have been found and are now corrected: