While the not dyed Shulker block make use of textures/blocks/shulker_top.png texture, dyed Shulker blocks don't use their respective block top texture.

Example:
The black Shulker block/box never use textures/blocks/shulker_top_black.png but portions of textures/entity/shulker/shulker_black.png

This is an issue because the UV map orientations for top and bottom faces are x,z reversed between Shulker block/box and entity.

See also: MC-108389