We have a custom Android app running on several WT6000 terminals. We've had no problems using the RS6000 Bluetooth scanner with the WT6000 terminal, until we upgraded the WT6000 from Android 5.1.1 to Android 7.1.1.
We performed some simple A/B tests, using the same version of our app, installed on 2 different WT6000 terminals, running on the same time on the same network. One terminal had Android 5.1.1 installed; the other had Android 7.1.1 installed.
On the Android 5.1.1 terminal each API call typically takes 200-400 milliseconds.
On the Android 7.1.1 terminal each API call typically takes 50-70 seconds. We even added a simple, isolated bit of code which just attempted to ping www.google.com but still saw the same delay of nearly a minute per HTTP request.
It seems that Zebra's version of Android 7.1.1 for the WT6000 is the likely culprit.