Everybody on this forum has their pet soapbox - I'm no exception to that.
My soapbox is to avoid brand-specific instructions with complex behaviors like FAL and its cousins. They came about because of the perception of needing to do those sorts of things in ladder. The ST is easier to understand, it is much more processor brand independent, and there is no need to research how the instructions work and their curious side-effects. If someone does not understand ST they really don't understand LD either.
Shouldn't the code inside your loop have some reference to the 'i' index?