If bluez cannot run, there's nothing gnome-bluetooth can do.

Confirming this on Fedora 27. Isn't this an SELinux issue?

This is stated in the logs:
13:42:29 dbus-daemon: [session uid=1000 pid=2028] Activation via systemd failed for unit 'dbus-org.bluez.obex.service': Unit dbus-org.bluez.obex.service not found.
<snip>
13:13:09 dbus-daemon: [system] Rejected send message, 1 matched rules; type="error", sender=":1.53" (uid=1000 pid=2217 comm="/usr/bin/pulseaudio --start --log-target=syslog " label="unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023") interface="(unset)" member="(unset)" error name="org.bluez.MediaEndpoint1.Error.NotImplemented" requested_reply="0" destination=":1.116" (uid=0 pid=6988 comm="/usr/libexec/bluetooth/bluetoothd " label="system_u:system_r:bluetooth_t:s0")
13:13:09 systemd: bluetooth.target: Unit not needed anymore. Stopping.
13:13:09 dbus-daemon: [system] Rejected send message, 1 matched rules; type="error", sender=":1.53" (uid=1000 pid=2217 comm="/usr/bin/pulseaudio --start --log-target=syslog " label="unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023") interface="(unset)" member="(unset)" error name="org.bluez.MediaEndpoint1.Error.NotImplemented" requested_reply="0" destination=":1.116" (uid=0 pid=6988 comm="/usr/libexec/bluetooth/bluetoothd " label="system_u:system_r:bluetooth_t:s0")
13:13:09 bluetoothd: Endpoint unregistered: sender=:1.53 path=/MediaEndpoint/A2DPSink
13:12:29 dbus-daemon: [session uid=1000 pid=2028] Activation via systemd failed for unit 'dbus-org.bluez.obex.service': Unit dbus-org.bluez.obex.service not found.
13:12:06 bluetoothd: Endpoint registered: sender=:1.53 path=/MediaEndpoint/A2DPSink
13:12:06 kernel: Bluetooth: RFCOMM ver 1.11
13:12:06 bluetoothd: LEAdvertisingManager skipped, LE unavailable
13:12:06 NetworkManager: <info>  [1517487126.8136] bluez: use BlueZ version 5
13:12:06 dbus-daemon: [system] Activating via systemd: service name='org.freedesktop.hostname1' unit='dbus-org.freedesktop.hostname1.service' requested by ':1.116' (uid=0 pid=6988 comm="/usr/libexec/bluetooth/bluetoothd " label="system_u:system_r:bluetooth_t:s0")
13:12:06 bluetoothd: Bluetooth management interface 1.14 initialized
13:12:06 kernel: Bluetooth: BNEP socket layer initialized
13:12:06 bluetoothd: Starting SDP server
13:12:06 systemd: Reached target Bluetooth.
13:12:06 kernel: SERVICE_START pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='unit=bluetooth comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
13:12:06 bluetoothd: Bluetooth daemon 5.48
13:12:06 systemd: Starting Bluetooth service...
13:12:06 kernel: Bluetooth: SCO socket layer initialized
12:32:39 dbus-daemon: [system] Failed to activate service 'org.bluez': timed out (service_start_timeout=25000ms)
12:32:39 dbus-daemon: [system] Failed to activate service 'org.bluez': timed out (service_start_timeout=25000ms)
12:32:14 dbus-daemon: [system] Activating via systemd: service name='org.bluez' unit='dbus-org.bluez.service' requested by ':1.93' (uid=1000 pid=4111 comm="/usr/libexec/gnome-contacts-search-provider " label="unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023")
12:21:35 pulseaudio: [pulseaudio] bluez5-util.c: GetManagedObjects() failed: org.freedesktop.DBus.Error.NoReply: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.
12:21:35 dbus-daemon: [system] Failed to activate service 'org.bluez': timed out (service_start_timeout=25000ms)
12:21:35 dbus-daemon: [system] Failed to activate service 'org.bluez': timed out (service_start_timeout=25000ms)
12:21:10 dbus-daemon: [system] Activating via systemd: service name='org.bluez' unit='dbus-org.bluez.service' requested by ':1.53' (uid=1000 pid=2217 comm="/usr/bin/pulseaudio --start --log-target=syslog " label="unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023")
12:20:48 NetworkManager: <info>  [1517484048.9751] Loaded device plugin: NMBluezManager (/usr/lib64/NetworkManager/libnm-device-plugin-bluetooth.so)
12:20:46 kernel: SELinux:  Class bluetooth_socket not defined in policy.

I noticed that Gnome Bluetooth does see the Bluetooth dongle after rebooting the system with the Bluetooth dongle inserted.

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