A study of 150,000 Florida felons given the right to vote found:
"One thing that limits the electoral impact of restoring ex-felons’ voting rights is that they turn out at particularly low rates. To demonstrate this, we first look to the population of ex-felons who were restored the right to vote under Crist and calculate what share voted in 2016.
We find that just 16 percent of black and 12 percent of nonblack ex-felons voted. (We defined nonblack as white, Hispanic, Asian, and other due to data limitations.)"
"The potential electoral impact of Florida’s ballot initiative is further limited by the fact that the ex-felons who do vote are not politically uniform. While black voters within this population overwhelmingly register with the Democratic Party (87 percent), nonblack voters within this population were more likely to register as Republicans (40 percent) than as a Democrats (34 percent). The fact that 26 percent of the remaining nonblack voters affiliate with neither party suggests that their votes may not reliably be cast for either party."
https://www.vox.com/the-big-idea/2018/11/2/18049510/felon-voting-rights-amendment-4-florida