Hi.
The problem described here was solved using a workaround.
Description
I always used Insync (python 2 support) without major issues. Since I updated to 3.0.27 version problems started to happen. Anyway, today I found a workaround to show the tray icon on polybar. (because sometimes it shows, sometimes not)
Solution
What I did was force insync to start after the polybar.
/$HOME/.config/polybar/launch.sh
[...]
#!/usr/bin/env sh
# Terminate already running bar instances
killall -q polybar & killall -q insync
# Wait until the processes have been shut down
while pgrep -x polybar >/dev/null; do sleep 1; done
# Launch bar1 and bar2
polybar --reload top &
insync start &
#polybar bottom &
#polybar top-left &
#polybar top-up &
Done, now I have the tray icon on polybar.
Advice
Anyway, it would be good to fix this issue in the next release.