Couldn't hurt to check.
When my flock had it, I did pretty much all the suggestions that you're receiving here... sanding perches, removing some perches, changing bedding, being uber-vigilant about cleaning, we added a "step" to make getting up and down to the roost easier, we added sand to a moist spot in the yard they like to hang out in, feeding extra supplements, etc...
We did so much over the span a few weeks trying to clear this up, but in the back of my mind I kept wondering... in 4 years, I've never had a problem like this... sure, occasional bumblefoot here and there, but not where so many birds had it. In the back of my mind I kept wondering... why now?
Another thing that was weird about my girls having it, is that treatment wasn't really improving the situation. I see in one of your replies that the soaks are helping, so your situation may be different from mine. In hindsight, I realize that even after soaking/wrapping/removing the bumble, the girls were still stepping on the sharp piece of wire so they couldn't heal. Once I sanded down the offending sharp piece of wire, most of the bumbles cleared up on their own, like
@dawg53 mentioned. I only had to treat the more serious cases.
Hope you're able to figure out the cause and get your flock all cleared up.