Imaging plugins absent from sampler instrument FX menu

Years ago I created a midi instrument using logic's multi-sample sampler and samples of the 180 year old organ in Leeds town hall. I've somehow gone all this time without realizing the entire imaging section of plugins are absent from the FX menu. For some reason, I'm pretty sure when I created this instrument, I set it to a 5.1 output, which of course removes imaging altogether, but even when I switch it to stereo, mono or multi output, I still can't get any imaging plugins to appear. Anyone have any idea what might be going on or any idea of how to fix? I really don't want to have to hunt down and process all of those samples again and create a new instrument :(