On the VNM model in the Fault Isolation setting is an automatic destruction setting to destroy models that have a contact lost state yet models are not being destroyed once this is enabled and the seconds have passed:
Contact Lost Model Destruction
Destruction Delay (sec)
This is tentatively scheduled to be fixed in NetOps Spectrum 23.3.7.
The workaround is to stop and restart the SpectroSERVER process and/or manually delete the models.