Hello snarf20,

have you set the Archive configuration for the Taglogging-Archives
in the Runtime settings of the WinCC Professional projekt ?
The default timeperiod-values for a single segment is one day, and
over all one week.
If you have not made an other setting, you get only data for 7 days.
Or the maximum size of all segments is to small.
In this case, the oldest segment is always deletet, if a new one
is created.

see the FAQ:
"How many single segments can be connected to the SQL server in PCS 7
without impairing performance?"

https://support.industry.siemens.com/cs/ww/en/view/34473263

This is valid for TIA Professional too.

Regards

Georg Berghof