We have dropped support for itemframes, which means SignShop is no longer protecting your linked item frames. Any user can now remove the items you have placed in them, unless you are using some other protection plugin to combat this. I suggest destroying your item frames, or getting a protection plugin to deal with it. This also means that any linked item frames have now duplicated your items. I'm sorry about this, but item frames were a real pain to deal with, and in order to make sure your server economy is safe from exploits, we had to drop support for them all together.
Due to a new implementation of the [worth] feature, you will need to update your version of Essentials to at least the latest release build (2.12.2) otherwise you will get a ClassNotFound exception.