Only thing I can say is I switched to flowering nutes around day 40ish, than gradually went up on the strength. Maybe you waited a bit too late for the flowering nutrients?
Could be but shouldn't they still budding due to their life cycle anyway? I don't get it....one thing I noticed the plants been spending lots of time growing new leaves out from the bud sites, but the buds are not getting fat....just hope the buds will start growing now.