You have to leave the focus of a field to correctly save the block in Layout Builder

Steps to reproduce

1. Install the patternkit_example and config it to use the blocks on the layout builder.
2. Go to any layout and add, for instance, the Example block.

If you add a text on a field and you keep the cursor on it and click Save, the value won't be saved.
If you add a text on a field, click outside of it, and click Save, the value will be saved.

I add a video to explain a little more myself.

This does not happen when you add the block at /admin/structure/block