The Linux binary for libQtBluetooth.so in qt-enterprise-linux-x64-android-5.4.0-rc_2014-11-13_13-34-01-89.run does not contain the Bluetooth LE backend.
Based on code behaviour on some minor disassembling the I'd say the default/non-functional backend is compiled into the package. The build output could confirm this theory.
As a consequence Bluetooth LE is completely disabled during the package creation which means the entire Bluetooth LE tech preview is not happening. Linux is the only platform that is supported during the Tech Preview.
This used to work in the beta package which would indicate that the package build environment has changed. The build environment must pass the following unit test:
which implies the availability of Bluez 4.101 or later headers.