When Samsung S8 is Android 7.1, bt hci log locates at Android/data. But when update it to Android 8.0, hci log cannot find in any folder. I also try to generate hci log through commands follow but it does not work neither. These commands works fine with my Pixel 2.
adb shell dumpsys bluetooth_manager
adb bugreport > BUG_REPORT.txt
This is tested and verified working for S8, S9, S10+ Android 8.0 through to 9.1:
Input *#9900# in the dial pad. An engineer mode menu will pop up.
Click Run DUMPSTATE/LOGCAT/. Wait. It may take several minutes for this to generate logs.
Click Copy To sdcard... or Copy to ext sdcard
/sdcard/logs will contain an extensive dump of system logs
/sdcard/logs/bluetooth/ will contain your timestamped btsnoop_hci_ log files