I’m certain you’ve caused a lock out with too much nutrient and if your problem didn’t show up because of that, the high alkaline wood ashes certainly did. I’d flush them out or you will loose them all. Seedlings don’t need very much nutrient at all and very small amounts when they do start to feed. You’ve got a ton of perlite in that substrate, don’t worry about compacting it.
Me personally, I’d ditch the hose water. That looks like bag soil and it’s got cal/mag buffer of dolomite lime. By adding more alkaline carbonates via tap water your going to accumulate your carbonate values and consequently fixation of pH. Use purified water either from an Reverse Osmosis purification (approximately 20ppm) or vapor distilled (0ppm)
Me personally for the flush purposes I’d use 0ppm as it can grab and help remove more of your accumulated elements in the soil. Then resume with RO water normally.
All small seedling need is a pinch of worm shit or very small pinch of something like insect frass as a sprinkle on top and watered in. When they’re this young they need to find their feet so to say, to set out roots and become established. Worm casting is ideal for such an application, it’s gentle and won’t burn, and adds back microbes.