It's me again.
This time, it's not something related to the mod directly, but to vanilla. You know how sometimes fluids remain stuck at decimal values? Because of that, if you're not using a pump to fill a fluid dematerializer, it will usually remain stuck at 49k/199k fluids depending on which one you're using.
And since they only teleport things when they're full, they won't even activate since this 0.x fluid is missing. (I kind of discovered that the hard way when my whole oil power plant shut down… Ahem.) Now it's possible to use a decider combinator with something like green if > 199k but that remains a makeshift solution.
Maybe you could change the behavior to enable the teleporter if it's more than 99% full rather than 100% full?