I love the dragons let me see if I can help tame them a bit. I agree with the others, I was a heavy Canna user, and think this is your downer here. I think the BioVeg is getting to them. Normally I would not introduce until after first week maybe 2-3 weeks or when I can tell signs in plant base nutes or food in the starting soil is toast and when doing so I start with 1/8 to 1/4 dose depending on when you start counting weeks. I also run 1/4 for a little bit and gradually start increasing around week 3-4 till I can hit 1/2. This is all strain dependent to some are eater some aren't. Rhizo is fine I use it in my soak water, mist water, and root water from start. Always seems to calm my stressed plants.
Also just for comparison I have 16 out of the 18 girls just germed and about every two to 3 days I give them about 100ml of water each with 2ml/2l Rhizo with mist in between or when top of soil drys. And I don't run a humidifier. Soil looks a little wet but not sure when you took pics you giving 300ml then bumped to 700ml, eod? kuckle test?
I know from your previous work you got it going on. I recently swapped from Canna to AN and know a little about Canna. Just hope to help where I can, especially with a special breed I love to follow and hope to grow oneday.