I've recently mixed some simple one-flavor juices that were delicious right at first, but within a day or so the flavor had become very weak. Has anyone else experienced this, and is there a fix? They're Capella flavors mixed at about 20%, 50-50 PG/VG base, sweetened with EZSweetz. I thought I read somewhere on this forum that adding a couple drops of lemon juice would make juices more stable, but now I can't find that thread again. Any suggestions?