You need to go to the Features and enable Oxygen 3.8 Fixes.
Missing drag handles inside structure panel.
In Oxygen 3.9 you don't need drag handles anymore. You can grab elements without them from whatever part of the element you want.
That's why we removed them from UI completely to clean up UI. But since we released it before Oxygen pushed the update users with 3.8.1 have problems dragging elements.
Oxygen 3.9.1 Introduced an entirely new HTML structure of the "Structure panel" and we optimized CSS for new Oxygen. It was pointless to work on something that will be replaced by Oxygen anyway in a matter of days.
This will be bring coloring and the icons as well to the Structure panel.
Missing default theme
The toggle was now working if you select the default theme. It was doing fallback to the dark theme.
Moved Clean breakpoint to top right corner
If you enable show breakpoint size it was covering clean values icon. Now icons are always showing and they are accessible.
We are compatible with Hy*r*g*n Copy Paste
Even if we use different coding approaches the same values are copied since we are copying Oxygen values and not creating new ones. That's why we are using the same JSON decoding standards and if someone gives you clipboard values you can paste it with Swiss Knife as well.
In case you want to roll back until Oxygen release 3.9 offically
You can log in to the shop dashboard and download Swiss Knife 1.3.7