I have killed many a flask. I usually kill Cattleya flasks so there will be a difference with my experience vs yours, but I have killed many a paph flask too. There are those who say you should take advice from those who have killed many to learn how they eventually learned how to grow it right. There are those who say listen to the professionals and take their advice. Then there's always whatever works for you works for you.
Having said that what finally worked for me was reading a book on seedling care which - miraculously - I had in my library and just never got around to reading. Its Bob Gordon's book imaginatively titled 'Orchid Seedling Care'. I have no idea if its even still in print. It stresses water quality.
In a nutshell it promotes a dome of some sort, the cleanest water you can find, and very very very dilute fertilizer. And low light.
I bought one of those clear file storage boxes at a stationery store and have my seedlings in there in my house for temperature control. They are doing wayyyy better than the ones I merely potted up and put in a shady place in the greenhouse. So much so that I'm considering getting off my fat *ss and buying another container for the GH seedlings which are still flaskling size after 7 yrs or so in the GH.
Nutshell advice = dome of some sort for humidity, inside house for temperature, low light, very very very dilute fertilizer - if any at all. Be very very careful. so far (touch wood) no mildew or pathogens with this technique. I'd say no plant losses either but that would tempt the orchid gods.
