Server & Client are using PulseAudio 6.0-2. Sometimes video-playback is blocked, but sound is streaming over TCP. After restarting PulseAudio on Client & Server a several times, video-playback is working again. I've tested video-playback on Firefox, Chromium, mpv & mplayer, all of them are having the same issue.
I've asked on Freenode and at least one other person said it's friend is having the same issue.
I'm new to the bug-tracker, so please tell me which additional details you need for debugging or reproducing.
Thank you!

Snippet of `pulseaudio -v` on server:

I: [pulseaudio] sink-input.c: Created input 1 "alsa_output.pci-0000_00_1b.0.analog-stereo for foo@foo" on alsa_output.pci-0000_00_1b.0.analog-stereo with sample spec s16le 2ch 44100Hz and channel map front-left,front-right
I: [pulseaudio] sink-input.c:     media.name = "alsa_output.pci-0000_00_1b.0.analog-stereo for foo@foo"
I: [pulseaudio] sink-input.c:     media.role = "abstract"
I: [pulseaudio] sink-input.c:     application.name = "pulseaudio"
I: [pulseaudio] sink-input.c:     native-protocol.peer = "TCP/IP client from 10.42.0.1:53549"
I: [pulseaudio] sink-input.c:     native-protocol.version = "30"
I: [pulseaudio] sink-input.c:     application.id = "org.PulseAudio.PulseAudio"
I: [pulseaudio] sink-input.c:     application.version = "6.0"
I: [pulseaudio] sink-input.c:     application.process.id = "25978"
I: [pulseaudio] sink-input.c:     application.process.user = "foo"
I: [pulseaudio] sink-input.c:     application.process.host = "foo"
I: [pulseaudio] sink-input.c:     application.process.binary = "pulseaudio"
I: [pulseaudio] sink-input.c:     application.language = "en_US.UTF-8"
I: [pulseaudio] sink-input.c:     application.process.machine_id = "d3f1fa9497a743628bb75d86e0d18f67"
I: [pulseaudio] sink-input.c:     application.process.session_id = "1"
I: [pulseaudio] sink-input.c:     module-stream-restore.id = "sink-input-by-media-role:abstract"


Config snippet to enable TCP streaming (Server):

load-module module-native-protocol-tcp auth-ip-acl=127.0.0.1;10.42.0.0/16
load-module module-zeroconf-publish


Error message when starting up PulseAudio on server:
W: [pulseaudio] server-lookup.c: Unable to contact D-Bus: org.freedesktop.DBus.Error.NotSupported: Unable to autolaunch a dbus-daemon without a $DISPLAY for X11
W: [pulseaudio] main.c: Unable to contact D-Bus: org.freedesktop.DBus.Error.NotSupported: Unable to autolaunch a dbus-daemon without a $DISPLAY for X11
W: [pulseaudio] protocol-native.c: Denied access to client with invalid authentication data.
W: [pulseaudio] protocol-native.c: Denied access to client with invalid authentication data.


Error message on client:
E: [pulseaudio] module-tunnel.c: Failed to authenticate
E: [pulseaudio] module-tunnel.c: Failed to authenticate