Keyboard sometimes doesn't work after unlocking the screen

Since about when Xfce was updated (but I also changed my system from Acer to Tuxedo in the meantime, so doesn’t need to be correlated), in about 1/4th of the the times when I unlock my screen, I can’t use my keyboard, mouse works fine. The one-time-solution is: Hit “Switch user” and unlock the screen again. The problems are:

  • I sometimes use full-screen-programs where it’s very hard to get out just without a mouse
  • it’s annoying

Thanks in advance for your help!