I've started to create a new face and I added 13 sequences with around 25 images on each. After the first 10, maybe 11 sequences I could upload the face to my watch, but when 13 were ready I've started to get "Watch face error. Try again later"
Looking in the developer console I saw that I got "413 Payload Too Large" response from the server.
So, I guess that the "size" of the face is too large. Is there any list with the limitations of the face?