I am not sure if it is related the cache issue, It is because I had try to use veeam administrator account to access the backup repository for testing on these 10 user PC before.
After that, even I change it back to user credentials, they still can find all of PC's restore point.
I finally solved the issue by :
Fully uninstall the VEB (Include all related LocalDB, components and registry) then reinstall it
And all VEB restore credentials are correct now!