Ok nostr:nprofile1qqsp2wk4p9awff35r50lmx2rltvjc059dx5vg0n9aq9jq8dg9rez9aspunjvm I did my quick research... Splicing is NOT available on LND nodes as of yet... Only with CLN and eclair. With this being the case and the majority of lightning nodes being LND for the individual user, I'm guessing Alby hub hadn't implemented it because it isn't available across the board.
Splicing is also relatively new and the bugs haven't been fully worked out yet. Are you running the hub yourself? If you're running it off of CLN or eclair you can use "ride the lightning" or the node directly to splice... But it won't be through the alby interface.
I bet you, if you give it a year or so it'll catch up.