With initially underperfoming boosted stories, it's worth looking at your tags again, and maybe adjusting them. I had one, for example, which had 'sport' and 'football' as tags, because it was about watching football championships and other sporting events in the chilled, international setting of European campsites.
It failed to take off despite a boost, probably because it was being shown to fans of actual 'grown men chasing their balls around' sport, and more specifically, 'pyjamas over plastic exoskeleton pretend rugby'.
They weren't interested, so brought the read ratio down and killed the boost. Read ratio on the first couple of days seems to be important for how much boost a boost can boost.
I wasn't really paying attention, and realised too late.
Don't be me!