I think you're supposed to wait until clump is 3 years old before removing canes.

Here is a link that might be useful: Bamboo

That might explain the unexpectedly severe shock the main clump is going through right now. It is still alive and the leaves unfurl in the mornings or after a good rain (which Florida is kind of lacking this time of year, but it soon curls the leaves back up and some are going yellow. I wasn't expecting this much shock from removing 8 culms/rhizomes. The potted rhizomes are also still alive, but going through similar shock. I am keeping them and the main clump moist with rainwater from my rainbarrel, but it is only the recent rains that really seem to have a noticeable effect.

What's the species of the bamboo?

Typically, you need a decent size root ball for a division to grow. That means dividing off an intact chunk...the larger the better. I will be surprised if any of the pieces you have replanted will survive.

As I mentioned, I don't know the variety (species). I am usually pretty good on that point having a list of all the plants in my landscape with both common and latin names. I am also usually pretty good at growing and propagating my plants, but I mostly deal with Florida natives and palms, bamboos are still a mystery to me, but my wife has been wanting one for years and so I finally took the plunge. When I purchased this bamboo there was a metal tag tied to one of the canes and I incorrectly assumed that at least the common name was on that. Upon getting it home, I realized all that was on the tag was a stamped number. However, comparing my bamboo with a list provided by a somewhat local bamboo grower, I would have to say it is either Golden Goddess or Ladyfinger, though I am leaning toward the former. If it weren't going through the severe shock, I would snap a pic for verification.

I will keep the culms sheltered and not keep my hopes up too much. If I do not see signs of growth by next summer I will chalk it up to a learning moment and wait a few years before attempting to divide again. I just hope it comes out of this shock before our 'cold' weather arrives.

Just a quick update, not that anyone is likely following this. Of the three pots of culms, one rotted to nothing and two are now putting out new shoots on existing canes. No sign of new culms coming up yet. The main clump still seems dormant though. It still has some green canes and green leaves on those canes, but there has been no sign of new growth yet. With the days lengthening and already very warm, plus the new growth on the potted culms, I keep hoping to see new growth on the main clump, but no dice. Yet. Keeping fingers crossed.