hostapd does not create a wifi network

Question

I'm trying to setup a wireless AP to share a wired internet connection over Wi-Fi.
It's a newly built PC, and at first I thought that the wireless card might be defective, however everything works correctly trying connectify under windows.
I chose a wireless card just for this scope hoping that it wouldn't give me problems (ath9k driver), but I can't figure out what I'm doing wrong.
The card is a TP-Link TL-WN781ND, with AR9285 Atheros chipset.

even the simplest configuration of hostapd with this .conf file

interface=wlan0
driver=nl80211
ssid=test
channel=1
hw_mode=g
country_code=IT

(same behaviour even without country_code) and launching it with sudo hostapd /location/to/hostapd.conf seems to run successfully, however it won't generate any network.
I'm scanning for Wi-Fi networks on 3 different devices (Android tablet, iOS phone, Ubuntu laptop) and the network doesn't show up in any of them.

the only warning/error that it gives me is this:

$ sudo hostapd hostapd.conf
Configuration file: hostapd.conf
Failed to update rate sets in kernel module    #<-- this one
Using interface wlan0 with hwaddr 64:66:b3:fa:df:1a and ssid 'test'

I'll paste here the output of launching it with -dd option:

random: Trying to read entropy from /dev/random
Configuration file: hostapd.conf
nl80211: interface wlan0 in phy phy0
rfkill: initial event: idx=0 type=2 op=0 soft=0 hard=0
rfkill: initial event: idx=1 type=1 op=0 soft=0 hard=0
nl80211: Using driver-based off-channel TX
nl80211: Use separate P2P group interface (driver advertised support)
nl80211: TDLS supported
nl80211: TDLS external setup
nl80211: Register frame command failed (type=208): ret=-114 (Operation already in progress)
nl80211: Register frame match - hexdump(len=2): 04 0a
nl80211: Failed to register Action frame processing - ignore for now
nl80211: Add own interface ifindex 3
nl80211: Set mode ifindex 3 iftype 3 (AP)
nl80211: Create interface iftype 6 (MONITOR)
nl80211: New interface mon.wlan0 created: ifindex=11
nl80211: Add own interface ifindex 11
BSS count 1, BSSID mask 00:00:00:00:00:00 (0 bits)
nl80211: Regulatory information - country=IT
nl80211: 2402-2482 @ 40 MHz
nl80211: 5170-5250 @ 40 MHz
nl80211: 5250-5330 @ 40 MHz
nl80211: 5490-5710 @ 40 MHz
nl80211: 57240-65880 @ 2160 MHz
nl80211: Added 802.11b mode based on 802.11g information
Allowed channel: mode=1 chan=1 freq=2412 MHz max_tx_power=20 dBm
Allowed channel: mode=1 chan=2 freq=2417 MHz max_tx_power=20 dBm
Allowed channel: mode=1 chan=3 freq=2422 MHz max_tx_power=20 dBm
Allowed channel: mode=1 chan=4 freq=2427 MHz max_tx_power=20 dBm
Allowed channel: mode=1 chan=5 freq=2432 MHz max_tx_power=20 dBm
Allowed channel: mode=1 chan=6 freq=2437 MHz max_tx_power=20 dBm
Allowed channel: mode=1 chan=7 freq=2442 MHz max_tx_power=20 dBm
Allowed channel: mode=1 chan=8 freq=2447 MHz max_tx_power=20 dBm
Allowed channel: mode=1 chan=9 freq=2452 MHz max_tx_power=20 dBm
Allowed channel: mode=1 chan=10 freq=2457 MHz max_tx_power=20 dBm
Allowed channel: mode=1 chan=11 freq=2462 MHz max_tx_power=20 dBm
Allowed channel: mode=1 chan=12 freq=2467 MHz max_tx_power=20 dBm
Allowed channel: mode=1 chan=13 freq=2472 MHz max_tx_power=20 dBm
Allowed channel: mode=0 chan=1 freq=2412 MHz max_tx_power=20 dBm
Allowed channel: mode=0 chan=2 freq=2417 MHz max_tx_power=20 dBm
Allowed channel: mode=0 chan=3 freq=2422 MHz max_tx_power=20 dBm
Allowed channel: mode=0 chan=4 freq=2427 MHz max_tx_power=20 dBm
Allowed channel: mode=0 chan=5 freq=2432 MHz max_tx_power=20 dBm
Allowed channel: mode=0 chan=6 freq=2437 MHz max_tx_power=20 dBm
Allowed channel: mode=0 chan=7 freq=2442 MHz max_tx_power=20 dBm
Allowed channel: mode=0 chan=8 freq=2447 MHz max_tx_power=20 dBm
Allowed channel: mode=0 chan=9 freq=2452 MHz max_tx_power=20 dBm
Allowed channel: mode=0 chan=10 freq=2457 MHz max_tx_power=20 dBm
Allowed channel: mode=0 chan=11 freq=2462 MHz max_tx_power=20 dBm
Allowed channel: mode=0 chan=12 freq=2467 MHz max_tx_power=20 dBm
Allowed channel: mode=0 chan=13 freq=2472 MHz max_tx_power=20 dBm
Completing interface initialization
Mode: IEEE 802.11g  Channel: 1  Frequency: 2412 MHz
nl80211: Set freq 2412 (ht_enabled=0 sec_channel_offset=0)
Failed to update rate sets in kernel module
RATE[0] rate=10 flags=0x1
RATE[1] rate=20 flags=0x1
RATE[2] rate=55 flags=0x1
RATE[3] rate=110 flags=0x1
RATE[4] rate=60 flags=0x0
RATE[5] rate=90 flags=0x0
RATE[6] rate=120 flags=0x0
RATE[7] rate=180 flags=0x0
RATE[8] rate=240 flags=0x0
RATE[9] rate=360 flags=0x0
RATE[10] rate=480 flags=0x0
RATE[11] rate=540 flags=0x0
Flushing old station entries
Deauthenticate all stations
wpa_driver_nl80211_set_key: ifindex=3 alg=0 addr=(nil) key_idx=0 set_tx=0 seq_len=0 key_len=0
wpa_driver_nl80211_set_key: ifindex=3 alg=0 addr=(nil) key_idx=1 set_tx=0 seq_len=0 key_len=0
wpa_driver_nl80211_set_key: ifindex=3 alg=0 addr=(nil) key_idx=2 set_tx=0 seq_len=0 key_len=0
wpa_driver_nl80211_set_key: ifindex=3 alg=0 addr=(nil) key_idx=3 set_tx=0 seq_len=0 key_len=0
Using interface wlan0 with hwaddr 64:66:b3:fa:df:1a and ssid 'test'
VLAN: vlan_set_name_type(name_type=2)
nl80211: Set beacon (beacon_set=0)
wpa_driver_nl80211_set_operstate: operstate 0->1 (UP)
netlink: Operstate: linkmode=-1, operstate=6
wlan0: Setup of interface done.
random: Got 20/20 bytes from /dev/random
RTM_NEWLINK: operst

to me everything seems to execute correctly except for that Failed to update rate sets in kernel module, even if I have to say that I saw someone who had hostapd working even with this message.
Can anyone help me or point me to the right direction?
Thank you very much

Solution

I managed to make it work.

Just before giving up and buying another card, I tried another PCIe slot... moved it from a 1x slot to a 4x slot... now it works perfectly!

Still receiving the Failed to update rate sets in kernel module but now it works as expected.