Sporadic success when searching for Document Number.
Solution
If you get partial success searching for document numbers, try stopping the Windows Search Service, delete the Windows Search database:
C:\ProgramData\Microsoft\Search\Data\Applications\Windows\Windows.edb
Then re-index the vault.
Notes and References
Hardware/Software Configuration
Platform: INTL64
OS: windows
OS Version: 10_1809
Product: SOLID_EDGE
Application: DOC_MANAGEMENT
Version: V221MP7
Function: SEDM
Ref: 001-10177809