I dont use Logic, but I can relate as far as the response you get from others or even the moderators of this forum, you might think is an obvious problem you overlooked at the very limited manual for the spark but you are not alone as far being a bit confused.
I was shocked to find out I was not going to be able record midi when used as VST in Cubase, I have so many cheap even free VSTs that would record midi, so the least I could spect from this product was at least the same, not more not less, give me the option to record like all of my VSTs.
So, I guess like you I am waiting for who knows, an update maybe ... Try routing Spark on Logic to come in as audio and you should be fine ....Good Luck