The upgrade from a pre-Jakarta instance to J or later migrates the CMDB to "TPP". This creates partition tables such as cmdb$par1 where the sys_class_path column can be left null, causing problems in a variety of CMDB list views. This is due to caching issues during the migration, and depends on exactly what queries get executed concurrently during the migration process.

The behaviour is impossible to reproduce consistently. The problem can occur frequently on production instances, but not on sub-prod. Even upgrading to Jakarta or later, the problem mostly will not occur, as it will need to involve a cache rebuild happening at exactly the wrong time.

• Look directly in the database for how many records in the tables cmdb$par1, $par2, etc. have a NULL sys_class_path.

• If working with a command-line client like "sudo snow query", remember to escape the $ symbol.

For example:
sudo snow query mycustomer "SELECT COUNT(*) FROM cmdb\$par2 WHERE sys_class_path IS NULL"

This issue is fixed in all currently supported versions. There is no workaround applicable. Please review the Fixed In section to determine the latest available patch your instance can be upgraded to. 

If the affected instance can not be upgraded yet, open an Incident with ServiceNow Customer Support and request to run the relevant cmdb sync script. This script is safe to run on a production instance presenting the problem, although there is a small performance cost (akin to rebuilding the schema cache), therefore it should be executed outside business hours.