You should check NPM 10.4 New Interface Graphs Not Updating
The issue you have faced is caused during upgrade process when "old" charts with Time Period have set to 2 hours. They are incorrectly transformed to "new" interactive charts with Time Period set to custom range where Begin Date is defined by time of ran of Configuration Wizard. This issue is fixed in NPM 10.4 SR which should be on your customer portal.
Thank you so much! All is well now, much appreciated.