Hi,

I am trying to extend the Story Block in order to provide support for a Transcoding plugin, I want to save a custom value in an attribute created by the said plugin.

I am able to extend and add a new setting to the Inspector Control, however the attributes aren’t being added to AMP Story Block.

/**
 * Add background video quality attribute to block.
 *
 * @param {object} settings Current block settings.
 * @param {string} name Name of block.
 *
 * @returns {object} Modified block settings.
 */
const addBackgroundVideoQualityControlAttribute = ( settings, name ) => {
	if ( ! enableTranscoderSettingsOnBlocks.includes( name ) ) {
		return settings;
	}

	//check if object exists for old Gutenberg version compatibility
	if ( typeof settings.attributes !== 'undefined' ) {
		settings.attributes = Object.assign( settings.attributes, {
			rtBackgroundVideoQuality: {
				type: 'string',
				default: defaultVideoQuality,
			},
		} );
	}

	return settings;
};

addFilter( 'blocks.registerBlockType', 'transcoder/ampStoryBackgroundVideoQuality', addBackgroundVideoQualityControlAttribute );

The above code checks block name from a constant of block on which the attribute has to be added.

Here is the current value of the constant.

// Enable Transcoder settings on the following blocks
const enableTranscoderSettingsOnBlocks = [
	'amp/amp-story-page',
	'core/video',
];

This is working as expected for the core block, however causing issue in case of the Story Block.

I believe this is a similar issue https://github.com/WordPress/gutenberg/issues/18709

Here is the full gist, which has current code used to achieve this https://gist.github.com/thrijith/8cff51c88151a08849faafccb7192d70

Changing hook priority for enqueue_block_editor_assets also doesn’t work.

Is this an expected behaviour?