nft error Could not process rule: No buffer space available

I'm switching from iptables+ipset to nftables, and as part of it, I need to
import a set containing ~2400 IPv6 networks. The file looks like this:

define elems = {
  2001:123::/31,
  ...
}

table ip6 mytable {
  set myset {
    type ipv6_addr
    flags dynamic,interval
    elements = $elems
  }
  chain output {
    type route hook output priority -150;
    ... ip6 daddr @myset reject
  }
}

And then "nft -f myfile.nft" fails with

netlink: Error: Could not process rule: No buffer space available

-- 
Best regards,
lilydjwg