You know, that very well could be what it is - I think you're right!
Big hole? Don't you mean "negative space" - lol
yes, you can see the aromatica is peaking out, but it hasn't taken off yet. Everything I put in there intially completely melted, but the new growth has started and that's what you're starting to see peek up over the rocks/wood. Not sure why it hasn't taken off completely yet.
Also one of my anubias barterii is starting to show signs of a deficiency - leaves are starting to lose their outer layer and show in the inner framework. It was just 1 leaf, so I wasn't worried much, but now a second leaf is starting to do it on the other side of the rhizome. My first thought was a K deficiency, but no other plants are showing any symptoms. I'll get a pic for help with it tonight.