I initially posted this topic in the character sheet forum, because I thought it was a character sheet issue, but after more testing, changing character sheets', etc., it looks like Compendium bug. When I drag a monster from the 5e Compendium to a map, the character sheet is created properly, but the Token is broken. There is a blank token created on the character sheet, and it wont drop onto the map. Here's how it looks: That blank space under default token is not empty: there is a bugged token there: I cant add a new token till i delete the current, invisible one. Once I delete the token, i can add my own token, but it has no linked data (HP, AC), so its pretty clunky.
