Hi there,
Can you share the contents of the reusable block?
The editor may freeze if the contents of the reusable block is coming from a third-party plugin like GenerateBlocks. It’s a gutenberg bug related to interaction between plugins and the reusable block. The theme has no control over this, unfortunately.
But it can work if the contents of the reusable block is a WordPress core block. (example: Columns block w/ a Paragraph Block).
AS for workaround, you may have to duplicate the contents of the reusable block and move it out, instead of duplicating the reusable block itself.