Sometimes losing item in top toolbar

I have “Move to Junk” in the top area to the right of “Refresh”. I have 4 items at the top and when I choose “Customize”, I see Move to Junk still there, but it’s not showing up. So far since using v9 for 5 days it’s shown up until yesterday and then again today. Yesterday I closed and reopened eM Client. That didn’t fix it, then I closed and waited about 20 sec and this time it showed up as normal.