hi tom,
i am glad i am able to help.
so i tried again, according to your guidelines with an 500kB and a 1.6 MB jpeg. also errors:
TypeError: attachment.sizes.thumbnail is undefined
https://localhost/dformhorak_dev/wp-content/plugins/ml-slider/assets/ml-slider.js?ver=3.5.1
Line 94
then i tried the plugin on another server/wp-installation. and there it works just fine. except for the bmp-behavior of course.
so, small pngs seem not to be a problem. it is a problem with my localhost installation.
i have to look into this further. if you have any suggestions, where to look – any help is welcome.
thanks,
arthur