I think this is a good development from their part as the tentacles of SegWit continues to spread further. I tried claiming a fork on Coinonmi at one time from a SegWit address and its was saying an invalid private key. I hope this has been resolved based on this upgrade.
What fork are you referring to? I think the coinomi segwit it still in beta.
Better to check your old bitcoin address and maybe your fork coins is there and verify when your segwit address created is it before fork or after?
Because if you created your segwit after the fork there are no fork coins in your segwit address.
Anyway, I never heard that someone could successfully claim their fork coins from a bitcoin segwit addresses unless if fork coins are also segwit support.