I had somewhat the same experience , got stuff off eBay , 6-8 plants packed in newspaper . It neither thrived nor died , just kinda chugged along shooting a new plant now and then . About 6 months or so later a butter dish of the stuff came up at a local club event , picked it up at a ridiculous price , like 2 bucks . This stuff took off ..... got 10 tanks pretty full , plus a massive amount in a small pond until the temperature dropped , plus enough for a RAOK a few weeks back . Best I can think is it depends on how it's shipped , maybe the first batch took a hit in transit . For me , under cfl's , low filtration , light to moderate bioload , and maybe light fert dosing (Flourish) every week or 2 I can expect my frog bit mass to maybe double in size every 6 weeks or so . Sometimes it gets kinda raggedy but it usually comes back fine . Be patient and wait for a RAOK when it gets warmer , someones always looking to unload their excess .