This is not a Byteball issue. It is a SegWit issue. Currently there is no standard message signing algorithm for SegWit addresses so you cannot sign a message using a SegWit address.
Thanks. I am surprised because my wallet allows me to sign messages using SegWit addresses.
Anybody know of any Bitcoin wallets that support SegWit and have "coin control" features (i.e., the ability to freeze addresses or send BTC from specific addresses)?
Which wallet are you using? I use Trezor and they did propose a signature algorithm and implement it but then they backed it out because the proposed algorithm did not get any traction with other wallets and exchanges. This really needs an official BIP so that we can get everyone to implement the same algorithm.