the Pi Zero only has 2.4Ghz wifi. Bluetooth uses 2.4Ghz
Depending on the Wifi Channel your pi is running on, my experience is the when running something like monitor or presence, the wifi performance is dire. Not sure if this is cross talk on the device itself, or just frequency clash, but I gave up using it for that.
So I Installed HASSIO on a RPi3 and connected it via RJ45 and it works perfectly with bluetooth tracker. Soon as I turn on the zero, wifi dies across the board. So if I want this to work I need to use LAN not wifi with bluetooth, this is a royal pain in the arse
Not sure if i am too late but I have also been struggling recently with a Pi Zero W running Bluetooth. What I found is that if I did a couple of Bluetooth scans (of a non present device) it would wipe out all 2.4 GHz WiFi traffic for about 10 seconds. It seems that the internal WiFi and internal Bluetooth do not work well together but the effects are not limited to within the Pi.
I have provided my experiences and observations in this thread but am finding it difficult to get any traction.
Anyway what worked for me is adding a USB Ethernet or WiFi dongle and turning off the internal WiFi. Impact on WiFi dropped to zero and it started behaving as expected.
Disabling the internal WiFi can be done by adding the line “dtoverlay=pi3-disable-wifi” to “/boot/config.txt”
Let me know if it works for you, good luck.