If Flexor does not match a record in your CRM that you are sure exists with a matching number, or one that you have performed a click to dial from in the CRM. It may even appear that Flexor does briefly match the number.
Check the Asterisk extenison configuration under Flexor Devices and Configuration.
If "allow callerid update" is checked, uncheck it and Save the change. Then Exit and Restart Flexor.