Compendium spells are currently not drag & dropable into NPC & Character sheets. DnD 5th Edition OGL

Title describes the issue.  Trying to drag and drop new spells, they won't get added.  Send help please.

When was the last time it worked in your game? Is this an issue in one single campaign, or does this also happen if you try do this in a new game?

So it's worked slightly in the past Now recently I'm trying to get it done with a friend. She has an ancient green dragon she was trying to plop the polymorph spell into.  It did used to work (she says) but i've not tried adding spells to npc's.  I tried dropping a fireball spell into a PC sheet and after SEVERAL ATTEMPTS it did work. No particular reason stoof out for why it worked the 5th or 7th time except for how long I held the fireball spell over the character sheet before releasing it in.  Dragging and dropping it in from the compendium. My friend says they were able to copy from the compendium into the npc ancient green dragon sheet but I didn't have the same luck with fireball, polymorph or otherwise.  That's all the observable hints I can give.  Edit: I just tried turning a giant badger into a spellcasting NPC in baldurs gate descent into avernus, there was no problems. HOWEVER the lost mines of phandelver game, with the ancient green dragon in still resists me, as does other npc's. I tried giving a zombie spellcasting and giving him wish spell. He would not accept the spell. The only things that are different is myself and a GM i've given GM permissions to for the game were online with me at the same time we were trying to deal with stuff.  Could that (SHOULD THAT) have been a factor?