3CX Phone 12 showing extension number instead of caller's ID

[eagle2]

Any resolution to the following problem: 3CX Phone 12 (SP3 for Windows, also for Android) is not displaying the incoming caller's ID. Instead of this own extension number & name are displayed, which makes no sense any way. In the same conditions X-lite and hardware SIP phones are displaying properly caller's ID.

In some cases the issue may be solved by re-installing 3CX Phone, but not always. Any idea ?