Interesting - going through something like this in my new 10 gallon NPT.
I planted heavy with crypts, najas, sunset hygro, needle leaf java fern, regular java fern, H. 'compact' corymbosa, H. difformis, L. repens, xmas moss, E. quadricostatus. 10 white clouds. Soil. 2 x 27W spiral CF, 1 x 15W T8.
Big NH3 outbreaks, which I'm dealing with by a daily regimen of Prime and Stability, and Seachem's "ammonia alert" as a monitoring device, until the tank is fully cycled. (Re-cycled, actually - used the black gravel that was in place in the tank, as well as the existing HOB - fully cycled with mulm, etc).
I've experienced moderate to severe plant injury, depending on the plant species. The corymbosa has really taken a beating, melting and translucent pretty generally; the needle leaf isn't doing well, and the wisteria plants have generally looked like they're experiencing deficiencies - yellowing and some leaf curling. Brown diatoms everywhere. I had thought much of this was due to the fact that most of these plants came from my 20H, hi-tech, and they were in shock due to a lower intake "charge" of light, CO2, ferts. But I also sniffed that it was wild water and soil parameters that may be at play.
In response, I'm leaving the tank untouched. Outside of feeding, and the daily dosing of Prime, Stability and 1 ml. excel, not doing anything else - no ferts, nothing. I plan on not changing the water, and seeing what happens, as long as the fauna exhibit good health.
From what I understand and this is not meant as a correction or alternative advise. The melting of plants first put into new Aquasoil has to do more with the modification of water parameters KH, PH, GH, and the plants needing more time to properly acclimitize to such modifications until the the Aquasoil matures sufficiently and the water parameters level off. There was a great big long thread discussing this, but I cannot find it. Basically people resolved the issue by letting the tank with aquasoil tank sit barren. Water was still put in and frequent water changes were done to address ammonia leaching from the substrate, but plants were only introduced into the tank two weeks or so after this and people claim they experienced no melting likely because the water parameters had sufficiently stabilized not to shock the plants as much. Take it FWIW.