Open Basic SMS/MMS Syncing Issues

I have 2 devices.
HTC 10 Sprint
Galaxy Tab S2 (SM-T713)

I have installed Join Both Devices.

At this point I am really just trying to get the SMS/MMS syncing to work.
I have enabled the Accessibility Settings.
Diagnostics passes everything.
I have the "Send Notifications" Enabled

I send a text from another phone. The HTC 10 and the Tab S2 both get the notification at almost the exact same time. I can see that both are getting the notification. I dismiss it on the HTC 10 and nothing is dismissed on the Tab s2. I dismiss it from the Tab s2 and nothing is dismissed on the HTC 10.

I tried the "send persistent" option and still there is no sync.

What am I missing? What am I doing wrong? I have uninstalled. Remove all devices. Everthing and I just can't get the syncing to work.