Our 3CX server was updated to 15.5 SP5 3 weeks ago. We have just discovered that *SOME* (not all) extensions will not function with CTI. Note that the firmware on the phone is the most recent revision (Yealink T46G 18.104.22.168). It seems that any extensions (IE: Extension #1) created prior to the update from 15.5.4 to 15.5.5 still function. Example: when the Windows App is configured with the Extension #1 loaded, and the desk phone configured with Extension #1, CTI functions normally. Call control is selected for "IP Phone". However, when we use an extension created after the update 15.5.5, CTI fails. Example: when the same Windows App (same computer) is configured with the Extension #2 loaded, and the desk phone configured with Extension #2, CTI fails. Both extensions (all tabs in admin console) are configured IDENTICALLY. We have verified this behaviour with 20 different extensions, 20 computer configurations, and 20 different Yealink T46G devices all on the most recent firmware and stock template. Help???