Got back to this today, and realized that the visibility issue was essentially due to all the columns being duplicated. I had made one or two minor errors in my rush the other day, including not noticing that every column was in the DGV twice. Once I got that cleared up, I also cleared up the visibility issue, and I don't really know how. I'm not sure which of the changes I made was the one that fixed the visibility issue, and I don't feel like breaking things again just to figure it out. One way or another, I was showing the columns wrong. Most likely, there was no visibility issue, it's just that, with every column being added a second time, I didn't notice that some columns were only there once, while others were there twice.

Anyways, the whole thing is resolved, and it is based off the CodeBank example that JMC posted in post #6. I expanded that example to include four different drop downs, and based off a more complex table, but it's the same structure.