I'm using D&D 5e by Roll20, and no not using popped out sheets. I'll check out the troubleshooting thanks. Edit: Unfortunately, nothing from that troubleshooting page is helpful here. The console logs shows the following when I drag&drop: VM242:8 Body drop!
VM242:8 Compendium item dropped onto target!
VM242:8 Drop handled, returning...
VM242:8 <a href="https://app.roll20.net/compendium/dnd5e/Spells%3AArmor%20of%20Agathys.json?plaintext=true" rel="nofollow">https://app.roll20.net/compendium/dnd5e/Spells%3AArmor%20of%20Agathys.json?plaintext=true</a>
VM242:8 Really updating character sheet values
VM242:8 Setting up repeating sections took until 9ms
VM242:8 Finding list of dirty attributes took until 9ms
VM242:8 Querytest took until 10ms
VM242:8 Attribute cache compliation took until 11ms
VM242:8 Set values (including auto-calcuating variables) took until 14ms
VM242:8 Took 16ms