So I created a workaround for this, it worked for me and its easier than manually adding a lot of clients, especially if you have mutiple vlans like I do.
First, from the IAP, backup the configuration. If you have not manually added a blacklist client, do so first.
I then use putty to connect to my IAPs and log the entire session. I use the command "show-clients" and then exit. I then open the log in excel and delete everything but the mac addresses of the devices you want to blacklist. I then concatenate the mac address along with the text "blacklist-client" so the text now reads "blacklist-client XX:XX:XX:XX:XX:XX"
Now go back to the configuration, open with preferred editing program. Find the area where the blacklisted items reside:
blacklist-time 43200
auth-failure-blacklist-time 43200
blacklist-client XX:XX:XX:XX:XX:XX
It here that you want to copy and paste all of the "blacklist-client XX:XX:XX:XX:XX:XX" items you have in your excel sheet. Save the config as something else in case something goes wrong, restore the configuration you just saved and your clients are added.