There is an available update, see Article ID195426 / ID165155. We highly recommend to update to the linked build ID195426
If you do not update, there is a
Workaround
Change the GUID column of the table from CHAR to VARCHAR.
With Microsoft SQL Server Management Studio you can do this by performing a right click on the table and then choose Design.
Navigate to column GUID and change the data type from char() to varchar(36).
Save changes by performing a right click on any column or in the white space and choose Generate Change Script... or alternatively use the key combination CTRL + S.
Depending on the settings of your Microsoft SQL Server Management Studio an error message may appear saying that Saving changes is not permitted. If that is the case navigate to Tools and click on Options... Open the tab Designers and choose Table and Database Designers.
Now deactivate the checkbox Prevent saving changes that require table re-creation.
Saving the changes should now work.
The next step is to change all entries of the GUID column which are NULL to a string of 36 whitespace characters.
In order to do so perform a right click on the table and choose Script Table as...->UPDATE to->New Query Editor Window.
Execute the following statement whereas TABLE should be the name of your table.
UPDATE [dbo].[TABLE]
SET [GUID] = ' '
WHERE [GUID] IS NULL;
GO
Values which originate from 7.11 should now be changeable in 7.20, and mixed data can be viewed in the extended trend screen.
Background:
With version 7.20 an additional column is introduced to the export tables. (Revision Text 76.4)
Also the format of the column [GUID] has changed. For local archive data the column was filled with 'NULL' from 7.20 on it is filled with 36 whitespace characters.
When now try to read a mixture of the old format and the new format, the new format will not be shown in the trend.
Additional, when try to manual correct these data in the archive revision or report generator screen, the changes will not be stored.