Make sure you are dragging by the name of the item and not the three lines next to the name. If that doesn't work, it's time for the troubleshooting guide. You say you've done Steps 1-2
of our Solving Technical Issues checklist (confirm you're using the latest non-test version of Firefox or Chrome; turn off all extensions, addons, and anti-virus), so if you'll do Step 3 and clear your cache that'll finish that part of the process. If doing that fixes the issue, just let us know. Otherwise, move on to Step 4 , and we'll need all that information, in addition to a link to the game (in the form of <a href="https://app.roll20.net/campaigns/details/xxxxxx/" rel="nofollow">https://app.roll20.net/campaigns/details/xxxxxx/</a> , not a join link) to further assist you.