today FlexRadio did release V3 of SmartSDR but xDAX and xCAT will not work with V3.
I did not expect such a big change at this time. My Flex is at my parents place since Xmas (I don't have any antennas where I live so I can either develop or operate remotely) and only after the Easter holidays I will be able to bring it here to do something with the apps. And I don't know how long it will take as my life is more than busy at the moment.
So if you need xDAX and xCAT for your operating you might have to stay with V2.4.9. Even V2.5.1 will not work as it uses the same changed API like V3.
Sorry about that..
73, Mario DL3LSM