Game crash because of an experimental warning

All my characters have a “uses experimental class” warning. This causes the game to crush when using an “open level” blueprint. In the editor preferences none of the experimental is activated, how can I find out what I used that causes the game crush?
All characters are AI and use behaviour tree, but i think its not experimental for a long time now.
Game crashes in 4.6 and in 4.7 preview 3, didn’t try in other versions

So I find out that crushing game experimental class is progress bar widget. What should I do? Is that a bag? It can not be that Im the only one using progress bar for HP representation

Update. Crushing game experimental class is not widget. I deleted it and the same result. Now my character have no experimental warning, but the game still crashes on open level if there is a character in the level

The only solution I found is destroying character before loading next level.