pack_format 4 and 5 does not work for block textures

Please attach the texture pack if possible

The file structure of that pack is outdated. Selecting the older pack format allows the game to detect that it's outdated and upgrade it automatically in-game. If you want to use the newer pack format, you'll need to upgrade it yourself.

For example, the blocks folder is now called block, and various textures like glass_blue are now blue_stained_glass