Get the automatic excerpt from a page created with gutenberg

The problem I have is im not getting the automatic excerpt (the_excerpt()) when I create a post with gutenberg blocks, If I put an image or something before the text it looks like gutenberg does not undestand it, if I put just text is ok but If I add images or a different block that is not text it is empty, is there a way to detect the first block of text in a post and use it like excerpt.

Thank you.