Vault Cache content disappears for few users

Hello All,

We are using EV 10.0.4 on Windows Server 2008 R2 Sp1.

EV Outlook addin version: 9.0.4

Client Operating system: Windows 7

We initially had couple of users who complained that the Vault Cache content is missing. However since then everday we have 2-3 users who complain the same.

When we perform the Reset, The hierarchy and contents are back however the issue reoccurs after few days.

Please provide pointers to get rid of the issue.

Regards