Reusable Blocks Get Broken after Crossposting
Please look on the screenshot below in order to understand clearly what I mean:

If you’re using Reusable Blocks on your website and faced with an issue like this, first of all I recommend you to consider using Block Patters. At least because Block Patterns are faster than Reusable Blocks. If it is impossible for your website, then please read this guide carefully.
First of all please check, that your are using 2.0 or above version of the plugin. If you don’t, you can upgrade from Network Admin > Plugins or download the fresh version in Member’s area.
Go to Network Admin > Settings > Crosspost and add wp_block
there in a list of allowed post types.

Once you do that, please crosspost the specific Reusable Blocks you’re going to use in posts for multiple sites in a network. You have to do it for every reusable block, yes.

That’s actually all. Now feel free to use Reusable Blocks in posts.
Please check the video below if something is still unclear for you.
Need more help?
- ACF fields are Empty on Crossposted Posts (Gutenberg)
- ACF Relationship Fields
- Bulk Crossposting
- Crossposting Doesn’t Work for a Custom Post Type
- Elementor Colors Mismatch
- How Plugin Works with Images
- How to Add Canonical Tag to Post Copies
- How to Connect Existing Post Copies
- Simple Multisite Crossposting: Hook Reference
- Terms (Categories, Tags) aren’t being crossposted
- WPML Compatibility