The roosts are pretty low so that shouldn't be an issue.I re-installed the roosts, they're about 10 inches up with the fresh bedding I put underneath.
It's weird because I've been keeping chickens for over 12 years and no bumblefoot ever, now 2 have it (new batch of chickens, maybe they're more susceptible?).
Are the birds with bumblefoot heavier breeds? I only find it popping up in my heftier chooks, none of the lighter ones (5 lbs or less) have had issues.