PH too high?

i some people will beg to differe, but ~6.5 is perfect. My nutes are buffered to hit that. I trust professional Ag company's research/experience. In this context, it could mean a slightly alkaline soil. if you can't impact it with lower ph'd irrigation over time, it's almost certain microbial or maybe too much of some slow release amendment (lime can do this, for example) -- cause and effect.. can't happen by coincidence, if not one of these 2 options, then something else. more importantly, the development of your seedlings will tell you soon enough. I'd try to push it down to 6.5 range or your intended target through irrigation. If not maybe some sort of gypsum or similar top amendment that will slowly acidify substrate and counterace the constant change caused by 'whatever' factor.