Well, you got me then. 19 years of this grow thing and still I wonder if I will ever know it all... Haven't used bloombastic so I can't comment other than, if there was any chance of a K issue, it should have covered it. I always lower nutes by at least 50% when using boosters and I usually use half of the boosters recommended dosage as well, until I have the pros and cons of said booster worked out for the strain.
If it was mine, I would double check that temps are constant and appropriate. I would triple check for a light leak (I know, I know, sorry, not trying to sound like a broken record) and make sure light supporting equipment (controllers, timers, etc) are functioning properly. Then, I would cut that f**king foxtail off and see if it comes back.
Has bud growth seemed to slow or stop or is she packing on at a decent rate?
Congrats by the way. For a first grow, you could have had allot worse happen. The only other advice I see fit to give at the moment is, cut the booster. Your new, which is great and I know you want to give her everything you can. Keep it simple, learn the strain and the basics, then dabble in boosters, additives, etc. A hydro shop will sell you everything and anything, tell you it's the best, and tell you a story or two to prove it. Not saying that boosters and addi's are bad, I have a few favorites. However, on your first few grows, they may do more harm than good. I never run a booster the first time I run a strain and I have been doing this a long long time. I like to get to know her first. Once I see what she does, I then tailor a recipe specifically for her.