Yepp, its just bunch of single vanity addresses.
Having conducted a couple of (brief) experiments... it would appear that Mycelium will no longer generate SegWit addresses from older,
uncompressed private keys. So, if you imported uncompressed private keys, it will now only generate the Legacy addresses for those specific keys.
However, if you import the corresponding
compressed private key... it will default to showing the SegWit (P2SH "3"-type and P2WPKH "bech32") addresses, but if you click "Receive" then it will give you the option of receiving to the "Legacy" (P2PKH) address from the dropdown.
So, as suggested by Coiner.de, maybe try "converting" those private keys using something like bitaddress.org (download, then run offline etc etc)... to swap from the uncompressed to the compressed form of those private keys. No need to use segwitaddress.org tho, just import those compressed private keys into Mycelium and hopefully that will show you the appropriate SegWit addresses.