UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36
Platform: 10575.55.0 (Official Build) stable-channel auron_yuna

Steps to reproduce the problem:
I am using a Web App talking over bluetooth to an android app. It's pretty basic just connect and send (a phone number).

What is the expected behavior?
chrome.bluetoothSocket.send() sends the correct string

What went wrong?
In production you only get the last 4 characters of the sent string (a phone number)

Did this work before? Yes 66.0.3359.203

Does this work in other browsers? N/A

Chrome version: 67.0.3396.87  Channel: stable
OS Version: 67.0.3396.87
Flash Version: 30.0.0.113

Since our Acer ChromeBooks updated to 67.0.3396.87 from 66.0.3359.203 our web app has stopped working. 

The web app connects to an android phone over bluetooth but since the upgrade chrome.bluetoothSocket.send() is sending pretty random data to the android app. Downgrading the chromebooks solves the problem but is obviously not a long term solution.

If I step through the chrome.bluetoothSocket.send() in the debugger I get a much higher chance that the correct data will arrive. In production you only get the last 4 characters of the sent string (a phone number).

Debugging the android app running normally I see mostly (but not exclusively) junk data arriving.