In 5.5, he complained about the data asset, the essence of the problem was that the data asset was one of the first to be assembled and referred to the base character, the base character in turn referred to the basic ability, which did not have time to assemble.
The problem arose due to changes in the compilation of BP in 5.5-5.6. By combining the logs, I was able to find the problem area.
The solution is very simple, make the data asset download a little later or change access to the base character through another asset.