thumbnail URL encoding problem

When uploading images I’m not seeing a thumbnail, just a placeholder with custom upload dir plugin activated.

My folder structure is defined as;

/%category%/%permalink%

The thubmnail URL in media manager is generated as;
http://www.domain.ext/wp-content/uploads/?post_type=product&p=194/the-product-150×150.png

However, the only URL that seems to work is replacing the “?” with “%3f”
http://www.domain.ext/wp-content/uploads/%3fpost_type=product&p=194/the-product-150×150.png

Could this be a rewrite problem somewhere ?

http://ww.wp.xz.cn/plugins/custom-upload-dir/