This is the same with me. I am trying to update a model’s description, and it shows that I have “0 characters left” when the whole description itself for the model when left unchanged has 14,304 characters.
Also, when you want to uplaod a model, you are limited to 1,000 characters for the description, which is a big step backwards from the older version of 3D Warehouse.
I also made a topic relating to it with pictures regarding the problem.
Having Issues With Model Descriptions