Same issue for me on Ubuntu 17.10. The snap package v0.20.30dev
does not show any output, not on the command line, not in the GUI. Installing the deb works fine.
Here is some debugging output if that helps:
$ SNAPD_DEBUG=1 snap run brave
2018/02/06 23:08:58.575762 cmd.go:212: DEBUG: restarting into "/snap/core/current/usr/bin/snap"
DEBUG: security tag: snap.brave.brave
DEBUG: executable: /usr/lib/snapd/snap-exec
DEBUG: confinement: non-classic
DEBUG: base snap: core
DEBUG: ruid: 1000, euid: 0, suid: 0
DEBUG: rgid: 1000, egid: 0, sgid: 0
DEBUG: apparmor label on snap-confine is: /snap/core/3887/usr/lib/snapd/snap-confine
DEBUG: apparmor mode is: enforce
DEBUG: checking if the current process shares mount namespace with the init process
DEBUG: re-associating is not required
DEBUG: creating lock directory /run/snapd/lock (if missing)
DEBUG: opening lock directory /run/snapd/lock
DEBUG: opening lock file: /run/snapd/lock/.lock
DEBUG: sanity timeout initialized and set for three seconds
DEBUG: acquiring exclusive lock (scope (global))
DEBUG: sanity timeout reset and disabled
DEBUG: ensuring that snap mount directory is shared
DEBUG: unsharing snap namespace directory
DEBUG: creating namespace group directory /run/snapd/ns
DEBUG: namespace group directory does not require intialization
DEBUG: releasing lock (scope: (global))
DEBUG: creating lock directory /run/snapd/lock (if missing)
DEBUG: opening lock directory /run/snapd/lock
DEBUG: opening lock file: /run/snapd/lock/brave.lock
DEBUG: sanity timeout initialized and set for three seconds
DEBUG: acquiring exclusive lock (scope brave)
DEBUG: sanity timeout reset and disabled
DEBUG: initializing mount namespace: brave
DEBUG: opening namespace group directory /run/snapd/ns
DEBUG: found base snap filesystem device 7:2
DEBUG: attempting to re-associate the mount namespace with the namespace group brave
DEBUG: successfully re-associated the mount namespace with the namespace group brave
DEBUG: found root filesystem inside the mount namespace 7:2
DEBUG: releasing resources associated with namespace group brave
DEBUG: moved process 5908 to freezer cgroup hierarchy for snap brave
DEBUG: releasing lock (scope: brave)
DEBUG: resetting PATH to values in sync with core snap
DEBUG: snappy_udev_init
DEBUG: setup_devices_cgroup
DEBUG: write_string_to_file /sys/fs/cgroup/devices/snap.brave.brave/tasks 5908
DEBUG: write_string_to_file /sys/fs/cgroup/devices/snap.brave.brave/devices.deny a
DEBUG: run_snappy_app_dev_add: /sys/class/mem/null snap_brave_brave
DEBUG: running snappy-app-dev add snap_brave_brave /sys/class/mem/null 1:3
DEBUG: run_snappy_app_dev_add: /sys/class/mem/full snap_brave_brave
DEBUG: running snappy-app-dev add snap_brave_brave /sys/class/mem/full 1:7
DEBUG: run_snappy_app_dev_add: /sys/class/mem/zero snap_brave_brave
DEBUG: running snappy-app-dev add snap_brave_brave /sys/class/mem/zero 1:5
DEBUG: run_snappy_app_dev_add: /sys/class/mem/random snap_brave_brave
DEBUG: running snappy-app-dev add snap_brave_brave /sys/class/mem/random 1:8
DEBUG: run_snappy_app_dev_add: /sys/class/mem/urandom snap_brave_brave
DEBUG: running snappy-app-dev add snap_brave_brave /sys/class/mem/urandom 1:9
DEBUG: run_snappy_app_dev_add: /sys/class/tty/tty snap_brave_brave
DEBUG: running snappy-app-dev add snap_brave_brave /sys/class/tty/tty 5:0
DEBUG: run_snappy_app_dev_add: /sys/class/tty/console snap_brave_brave
DEBUG: running snappy-app-dev add snap_brave_brave /sys/class/tty/console 5:1
DEBUG: run_snappy_app_dev_add: /sys/class/tty/ptmx snap_brave_brave
DEBUG: running snappy-app-dev add snap_brave_brave /sys/class/tty/ptmx 5:2
DEBUG: running snappy-app-dev add snap_brave_brave /dev/pts/slaves 136:*
DEBUG: running snappy-app-dev add snap_brave_brave /dev/pts/slaves 137:*
DEBUG: running snappy-app-dev add snap_brave_brave /dev/pts/slaves 138:*
DEBUG: running snappy-app-dev add snap_brave_brave /dev/pts/slaves 139:*
DEBUG: running snappy-app-dev add snap_brave_brave /dev/pts/slaves 140:*
DEBUG: running snappy-app-dev add snap_brave_brave /dev/pts/slaves 141:*
DEBUG: running snappy-app-dev add snap_brave_brave /dev/pts/slaves 142:*
DEBUG: running snappy-app-dev add snap_brave_brave /dev/pts/slaves 143:*
DEBUG: running snappy-app-dev add snap_brave_brave /dev/uhid 10:239
DEBUG: run_snappy_app_dev_add: /sys/devices/pci0000:00/0000:00:02.0/drm/card0 snap_brave_brave
DEBUG: running snappy-app-dev add snap_brave_brave /sys/devices/pci0000:00/0000:00:02.0/drm/card0 226:0
DEBUG: run_snappy_app_dev_add: /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-DP-1 snap_brave_brave
DEBUG: running snappy-app-dev add snap_brave_brave /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-DP-1 0:0
DEBUG: run_snappy_app_dev_add: /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-DP-2 snap_brave_brave
DEBUG: running snappy-app-dev add snap_brave_brave /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-DP-2 0:0
DEBUG: run_snappy_app_dev_add: /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1 snap_brave_brave
DEBUG: running snappy-app-dev add snap_brave_brave /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1 0:0
DEBUG: creating user data directory: /home/account/snap/brave/16
DEBUG: requesting changing of apparmor profile on next exec to snap.brave.brave
DEBUG: loading bpf program for security tag snap.brave.brave
DEBUG: read 6104 bytes from /var/lib/snapd/seccomp/bpf//snap.brave.brave.bin
DEBUG: raising privileges to load seccomp profile
DEBUG: dropping privileges after loading seccomp profile
DEBUG: execv(/usr/lib/snapd/snap-exec, /usr/lib/snapd/snap-exec...)
DEBUG: argv[1] = brave