Watermelon & StressKiller

Well week 6 in soil. The stress killer is trooping along a per normal. No issues and it’s looking great. The watermelon is a bit weird and not something I’ve seen before. Last week I had the brown crispy spots appear on the larger leaves and immediately added some cal mag thinking it’s was a magnesium deficiency. No change but it hasn’t got any worse so I added a bit more in yesterday’s feed. The strange part is the plant hasn’t started to flower, it’s just pushing more leaves - see pics Hopefully it will start flowering soon. Temps are good and I’m on a 20-4 light cycle so maybe the cause of the brown spots is also preventing the switch. If anyone reading this cares to comment, I’m open to suggestions