header_image hook doesn't update get_theme_mods()

[strarsis]

Related: [WordPress WP Display Header plugin](​https://wordpress.org/plugins/wp-display-header/)

The current header image is modified using the theme_mod_header_image hook.
However, in get_header_image_tag(...) the function get_custom_header() returns the default header data (including the non-updated URLs) while get_header_image() correctly returns the new header image URL.

Using wp_calculate_image_srcset(...) with the correctly returned new URL as $image_src argument but with the non-updated $image_meta from get_custom_header() no sizes/srcset attributes are rendered at all - just the img element with src to the full resolution image file URL.

[strarsis]

How can I speed up/improve the process?

[obenland]

Version 6 of WP Display Header should fix this issue.