Icon-sender not working as expected

I am running xfce on dom0.
Sometimes I reach into a state where task bar icons appear as 3d cubes instead of the app icons.

Most app icons do not appear and I was trying to find a workaround but when I run ‘/usr/lib/qubes/icon-sender’ once, the issue is mostly resolved. Now, only a fraction of icons still remain to appear as cubes. And this solution persisted after rebooting the appVM.

I am wondering as the appVM had an icon-sender process running already. I had just invoked another one and just killed it. So I think the icon-sender may have an issue.