GenerateBlocks doesn’t have its own paragraph block. It uses Gutenberg editor’s default paragraph and heading blocks for its text contents.
Perhaps what you mean was Gutenberg columns.
Currently, there’s no way to automatically convert posts and pages from Gutenberg columns to GenerateBlocks Columns. I’m afraid you’ve have to edit all posts and pages layouts from the default Gutenberg columns to GB columns manually.
A wise man once said:
"Have you cleared your cache?"