9900 overshooting KV

Hi I have a system that has no errors being reported but while testing I found the KV in some shots( mostly higher and max dose shots, ) are over 6% of kv on c arm and monitor from the reading on my meter. Some are as much as 15% higher on the meter. Ive tried a different meter and get the same results. Ive done filament cals and saved to system twice. The complete generator cal has been done . Ive tried a new high voltage reg pcb