I’m having troubles with BLE sensors in hass.io. The BT chip in RPi3 is crashing often and when I get data, it is spiky. I’m not sure are these issues related, but searching around I’ve learned that in newest kernel updates, BT has become very unstable. For data spikeness, one suggested workaround has been to decrease UART rate in RPi3 running hass.io.
I think the problem you were seeing is because the BT chip and WiFi chips use the same antenna. The other possible option would have been to use a wired network connection and then disable wifi.
Hmm, not sure, since wifi and BT worked nicely together until ~early December. I started looking around the internet and it seems that newest linux kernels include some bug or so causing this issue.