I had a lot of slaves stored up in Parabela, and wanted to move them to the Mt Pangeaus mine sites. So I put them in a group with a unit of scout cavalry as escort, but it put the cavalry at the head of the column, and those at the back rebelled. This then required a lot of attention to defeat and recapture the rebels, and get them moving again.

Maybe slaves in a group with a combat unit shouldn't rebel. Would make move them around easier

I also have to say that I find escorting slaves to be a bit fiddly since there is no option to have groups move at the rate of their slowest unit. As a result, I've made three attempts to escort slaves to a mine in Dalmatia, each time ending in a rebellion when my attention was diverted elsewhere.... I realize that there are multiple existing solutions to the problem (closer oversight, use workers instead, etc.) but it would be nice to be able to reliably escort slaves without having to babysit them.