If you're on Windows 10, check and see if you can drag and drop files in a normal file explorer window. If not, you'll be having the same issue as i was. This will run a fresh instance of explorer, and you should be able to drag and drop again. You might need to restart ableton to see the effect there.
Can I drag mp3 into Ableton?
Re: Can't drag and drop mp3s in Live
In the past to drag and drop any files from the Windows Explorer to Ableton you need to open Ableton as what you be logged on in your windows OS. If you logged in as Admin in Windows, open Ableton with admin permissions and you can drag and drop any file.
How do you drag clips in Ableton?
Method 1: Drag and drop via Tab key
In the Session View, click to select the clips you want to transfer - individual ones or a multiple selection - click-hold one of the selected clips, hit the Tab key to switch to the Arrangement view, then drag the clip to the desired position in the timeline and release - simple!