Was it cooked or the cold set stuff? Boiling gelatin can weaken it. Or if you didn't puree as much, you wouldn't have had as much liquid so there just may not have been enough to hold everything together. Maybe try straining the solids, measuring the liquid to make sure you have enough and then mixing it back together. You'd probably only have to go through that once to know how much extra you would need to add..
Cold water to set the gelatin but this recipe requires the water + sugar mix to be heated. It may be I got it too hot but I poured it into the cold fruit puree. Never thought of that. All the other ones I do I only warm the liquid.
Did another one last night, not the same flavor, and it came out fine so the amount of liquid was ok.
What I ended up with yesterday morning was like chunky soup, thickened but not set.
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