amwps This could be partially related to a feature of the PNG image, but more importantly, it's about outdated PHP GD image functions on your server. It returns a warning (not "error"), and therefore the image does not output properly on first response. On secondary response, it loads fine because it's already cached.
On my server, it works correctly, also on first load.
This is some image library on server that needs to get updated. Likely related to PHP GD, but depends on how you setup and installed the PHP/server.
