23B: Manage Customers Telephone Number sometimes Displayed as Asterisks

Summary:

On Manage Customers, the Telephone number at account level is sometimes displayed as asterisks rather than showing the number.

Content (required):

On Manage Customers, users have displayed the primary phone number on the account records. For some customers accounts, the phone number is replaced with asterisks:

The issue does not affect all customers, and doesn't consistently affect the same accounts - sometimes the phone number will display, others not, for the same user. Its not related to data access, as the user community reporting the issue have the same access. The problem also happens in production and UAT. We've tried different browsers, clearing cache, but the problem recurs.