Inventory Data is missing for random dataclasses.

NA

The option to keep history is selected for a data class but the history table does not exist.

dataclasses showing query will show any dataclasses that have the problem.  You can then use the console to deselect the Keep History option or the query below this with the results of the first.

select distinct dc.DataTableName, dc.KeepHistory, dc.Description, dc.CreatedDate, dc.ModifiedDate, dc.PurgeData, dc.PurgeKeepDays, dc.PurgeMaxRows
from dataclass dc
 join sys.objects so on so.name = dc.DataTableName
 join sys.dm_db_partition_stats ps on so.object_id = ps.object_id
 left join sys.objects so1 on so1.name = dc.HistoryTableName
where KeepHistory = 1 and ps.row_count>0 and so1.name is null

update DataClass
set KeepHistory = 0
where DataTableName = 'ENTER THE NAME OF THE DESIRED TABLE FROM THE FIRST QUERY'