Update to 20.04: Missing icons and icon alignments
Solution 1:
Try resetting the icons to the standard icon theme (eg. Yaru).
Had the same issue. I was using a non-standard icon theme called "paper" that is not available for focal.
Changing to a preinstalled icon theme using "Tweak Tools" solved both problems for me. "appearance" tab in Tweak Tools where one can change the icon theme