Spells from Compendium not dropping onto Sheet

When I drag a spell from Compendium and drop it on my character sheet, it never appears.  I've tried duplicating the character and doing it with another character sheet.  It just doesn't work.  I've also tried multiple browsers, flushing the cache, and the other first recommended actions.  The spell appears in the attribute "kingdom_drop_name" but never appears in the spell list for the PC sheet.  

Hi Sarrish! This sort of behavior is highly dependent on the sheet being used. Can you identify it? The D&D 5th Edition by Roll20 Sheet?  Also, is the sheet engaged with the window or popped out on its own? The latter will not work.

It is the 5th Edition sheet by Roll20.  No, it is not popped out.  

I've tried the copy/duplicate character, clearing cache, other browsers, removing the token and adding it back, and archiving and restoring the PC.

I've rebuilt the PC several times and used Transmogifier to copy it to another game and try it there, with the same result.  

I finally got it to work,  I went to the Core page and did a drag/drop of an inventory item, then went back to the spell page and now I can drop spells from Compendium.  

Hmm. I'd like to try and duplicate this. Can you give some step-by-step instructions to duplicate this behavior?

I would try to drag/drop spells to the spell sheet generated using Charactermancer.  At first, I was able to drop a couple of spells, but then it stopped.  I tried all of the steps above, duplicating, copying the character to a different game, etc., but the spells I tried to add would never appear.  I went to the Core page and added an inventory item, in this case, a Weapon of Warning.  Then I went back to the Spell page and tried to drop Charm Person on the sheet, and this time it worked.  I was able to add the rest of the spells after that.  It seems to be working well now.  Maybe dropping an inventory item flushed a queue and allowed it to start working again.  

Very strange. At least you have a workaround.