In the first part of the level 1 certification exam it tells you to create a new list using the SKU.csv file they give you. The SKU.csv file you download ends up being multiple files in one folder. When I try to import the one of the attached files (SKU) into my new list (P3 SKU) nothing happens on my screen. Then on the next question when I try to import the file (SKU Volume.csv) into the new module nothing happens as well.
I did the same thing during the learning activities (import, then upload new file) and the data would easily transfer into the list or module.
Can you check your SKU list?, have you define parents for SKU list? ,If yes and still you are not able to add item in SKU list, then please send some screenshot of your SKU list and after import what error are you getting and also mapping.
It works perfectly for me, Please try to clear your cache & cookies then try to upload again or try at some different browser, if still it doesn't work for you then raise a ticket to Anaplan support at firstname.lastname@example.org