I see a bunch of folders under our team site that were created by other users that are empty. This happens because all the content in the folders are checked-out by the user(s); therefore, no other users are able to see them. Here are instructions on how to check-in ALL of the content in single action.
Go to Site Settings by clicking on the gear icon located in between the alert bell and help question mark icons in the upper left-hand corner of the page next to your name.
under Site Administration section (which is on the 3rd from the top in the left column), select "Content and Structure" (5th from the bottom in that section's list).
At the first page there is a list of the files with a "default view" in the toolbar on the right section. Drop this down and choose "Checked out to me". Navigate to the folder where the files you wish to check in are located.
This will list all of the files checked out to you within the site and subsites you are in. Click on the multiple selections icon to check the boxes next to all checked out content or alternatively you can check the checkboxes individually to select your items and in the actions drop down choose check in. You'll be prompted one time for the comment to check the file(s) in with, so be sure you want to replicate that comment across all selected items for the Version History. Once you click on the "OK" button, all the content will be checked-in and other users will be able to view what you have uploaded.