Spell Drag and Drop from Compendium

As DM I am creating a NPC. I am trying to drag and drop spells from the Compendium which we have always done in the past. I get the Accepting Drop from Compendium Notice, but nothing enters into the sheet. After reviewing other Community posts on this, I tried recreating the NPC, but had the same problem. I tried a Monster and a Character already in the Curse of Strahd module with the same effect. Then tried one of my PCs, again with no effect. I really appreciate your help in advance.

I've seen this recently. Make sure you have gone into the NPC's settings and turned on "Spellcasting NPC".

I apologize for not responding soon Keith - like many we just adopted Roll20 from our home game and am getting used to knowing where to look. The issue resolved itself when I logged out and logged back in. I assume it was a ghost in the machine.  Thanks again for your quick response. I have seen your contributions in the forums and appreciate the guidance. ~ Jason