FM150: adding new link in qmap-passthrough mode fails with -EINVAL

E.g.:

$ sudo strace qmicli -d /dev/cdc-wdm0 --link-add="iface=wwan0,prefix=qmapnet,mux-id=3" -v
...
write(1, "[31 jul 2021, 16:25:05] [Debug] "..., 54[31 jul 2021, 16:25:05] [Debug] Using static mux ID 3
) = 54
access("/proc/net", R_OK)               = 0
access("/proc/net/unix", R_OK)          = 0
socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0) = 7
ioctl(7, SIOCGIFINDEX, {ifr_name="wwan0", ifr_ifindex=53}) = 0
close(7)                                = 0
sendto(6, {{nlmsg_len=92, nlmsg_type=0x10 /* NLMSG_??? */, nlmsg_flags=NLM_F_REQUEST|NLM_F_ACK|0x600, nlmsg_seq=1, nlmsg_pid=0}, "\x00\x00\x07\x02\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\x08\x00\x05\x00\x35\x00\x00\x00\x0c\x00\x03\x00\x71\x6d\x61\x70"...}, 92, MSG_NOSIGNAL, NULL, 0) = 92
poll([{fd=3, events=POLLIN}, {fd=5, events=POLLIN}, {fd=6, events=POLLIN}], 3, 5120) = 2 ([{fd=3, revents=POLLIN}, {fd=6, revents=POLLIN}])
read(3, "\1\0\0\0\0\0\0\0", 16)         = 8
write(3, "\1\0\0\0\0\0\0\0", 8)         = 8
recvfrom(6, {{nlmsg_len=112, nlmsg_type=NLMSG_ERROR, nlmsg_flags=0, nlmsg_seq=1, nlmsg_pid=154348}, {error=-EINVAL, msg={{nlmsg_len=92, nlmsg_type=RTM_NEWLINK, nlmsg_flags=NLM_F_REQUEST|NLM_F_ACK|NLM_F_EXCL|NLM_F_CREATE, nlmsg_seq=1, nlmsg_pid=0}, {ifi_family=AF_UNSPEC, ifi_type=ARPHRD_RAWIP, ifi_index=0, ifi_flags=0, ifi_change=0xffffffff}, [{{nla_len=8, nla_type=IFLA_LINK}, 53}, {{nla_len=12, nla_type=IFLA_IFNAME}, "qmapnet2"...}, {{nla_len=40, nla_type=IFLA_LINKINFO}, [{{nla_len=12, nla_type=IFLA_INFO_KIND}, "rmnet"}, {{nla_len=24, nla_type=IFLA_INFO_DATA}, "\x08\x00\x01\x00\x03\x00\x00\x00\x0c\x00\x02\x00\x01\x00\x00\x00\x0d\x00\x00\x00"}]}]}}}, 512, 0, NULL, NULL) = 112
write(2, "error: couldn't add link: Could "..., 127error: couldn't add link: Could not allocate link: Failed to add link with mux id 3: Netlink message with transaction 1 failed

$ sudo qmicli -d /dev/cdc-wdm0 -p --get-expected-data-format
qmap-pass-through
$ sudo qmicli -d /dev/cdc-wdm0 -p --get-wwan-iface
wwan0
$ sudo qmicli -d /dev/cdc-wdm0 --link-add="iface=wwan0,prefix=qmapnet,mux-id=3"
error: couldn't add link: Could not allocate link: Failed to add link with mux id 3: Netlink message with transaction 1 failed