Q: MBA 10.10.4 not receiving iPhone 5s ver 9.1 calls

I have double and triple checked all settings and they seem to mirror exactly what is on my iMac.

I got my first iPhone a few days ago and set it up to send/receive calls on my iPad, iMac and MBA. The iPad and iMac are able to send and receive calls but my MBA can only call out, it won't pick them up. I have attached a screen shot showing what I get when I call comes to it.

I was wondering if there is a Library/Preference file that I can delete?

I have tried logging in and out of iCloud on the MBA and iPhone, restarting them, shutting them down completely and restarting them and that hasn't helped. Any advice would be helpful. And YES, I am on the same network, settings are checked for FaceTime & iPhone to allow calls, number is entered into FT to accept and make calls (which does make calls. just not able to answer), etc.

I fear it is some obscure setting or preference that is interfering with FaceTime showing the "accept call" button. I have tried it with FT being open and with FT "quit". If FT is not launched or "open" then no alert is presented on screen. I am using a landline to call my iPhone number. The iPhone rings, the iMac rings and the iPad rings. The MBA does not ring, even though FT is set to allow "ringtone (default) just like the other 2 devices.

If FT is open/launched then I get this notification on my MBA DURING the ringing process that I can hear on the other devices:

If I click "view", I get this on my MBA:

Thanks to anyone with insight.

Sandi