Not sure what is going on but today I created a new folder in my web editor sketchbook and it does not appear when I try to move sketches to that folder. The first folder I created is there, but sometimes it disappears and I have to reload the page to get it to show up again. Also when you right click to cut/paste, the menu that pops up is covered up by the surrounding web interface so you can't click on the copy function for example unless your cursor is near the bottom of the sketch editing screen.
There is currently a 3 folder deep limit so make sure you are not trying to make folders past that limit as they will often just disappear without showing any error.
The other aspect deals with empty folders.
If you make a folder but don't place anything in it right away but maybe hit refresh for the page it may also disappear.
To overcome that you should place something in the folder right away by maybe copy a sketch into there.
The folders are not "folders" as we understand them but "tombstones / markers" as they are often called in IT.
They are just pointers to something and not actual containers.
Cut and paste is also limited slightly as things are done via a "WEB INTERFACE" so most often it is better to use the shortcut keys such as CTRL V and CTRL C etc. (the old way).
@TryChick could you send us a screenshot of the copy/paste UI issue? Thanks!