When I had my amazon in my 20 gallon, it was doing wonderfully.... and I only had 0.9 or less watts per gallon. Now with it in my 48 with 2.7 watts per gallon, its doing just ok.
They are pretty heavy root feeders so either the substrate that you have in the new location is not enough for it or it has gone a little dormant from the move. It should pich up here in a few weeks or you could give it a root tab or two.
It entirely depends on the species of Amazon Sword (Echinodorus sp.)
There are many including sub-varieties. If you can identify the species then we may help furthur. One common attribute to swords is that they love a nutritious substrate.