I needed to create zip packages from the folders, the way I used to do all the time: right-click on the folder or file, from the menu: compress here using zip/tar.gz.
This time, I tried many times and no zip files were created. I tried tar.gz files, the same. So I launched the Ark UI and saw this:
Ah, the archives are hidden! They don’t have . in my case but still are somehow hidden. I forgot that although I had “show hidden files” setting on the main user folder, in the subfolder I have to enable it again.
So the Ark is working. The only issue is that add and search buttons are not active from some reason. Since I don’t use them too often, it’s not a big problem.