VNA models in Spectrum are deleted and recreated after enabling and disabling the VNA integration.
Spectrum 10.2.3 and below
Before enabling VNA Integration, if ACI models are discovered in 10.2.x and then the VNA Integration is enabled and disabled, the ACI Models are getting deleted and recreated.
There is a database change in Spectrum 10.3.0 which addresses this issue. No fix available for 10.2.x as this database change can not be back ported.