The current interface only supports core post meta sources registered through register_post_meta(). Custom binding sources (like ACF fields) require manual code editor bindings until future WordPress versions expand interface support.
Meta field types must match block attribute types using JavaScript type system conventions. Use “number” for both integers and floats since JavaScript doesn’t distinguish between them like PHP does.
Only single meta fields appear in the interface – multiple values for the same key aren’t supported. The interface needs unique field identification to establish proper bindings.
Bindings are block-instance specific, not global. Each bound block stores its own binding data, and deleting the block removes the binding. For persistent bindings, use block variations or content locking strategies.