This is a known bug in Sticky Jumper Bombz 1.1.0. Updating to 1.1.1 (released a month ago) should fix it.
Edit: Basically it was missing the PRESERVE_ATTRIBUTES flag, which stopped working (and was treated as always on) in TF2Items 1.5.3 around the time Sticky Jumper Bombz 1.1.0 came out in October 2013... but TF2Items 1.6.0 was released to fix that bug.