MT7610E: STA mode not working correctly. Unable to authenticate to AP

I am having a lot of troubles using the MT7610E as STA. Currently I am testing these two devices using the latest code in master:

• TP-LINK TL-WR902AC (MT7628 + MT7610E)
• ASUS RT-AC51U (MT7620 + MT7610E)

Both devices are not able to connect as STA to any AP. I tried changing channel (36, 100, 165), with or without encryption, using Qualcomm or Mediatek HW as AP without any luck.
The log says:

wlan1: authenticate with XX:XX:XX:XX:XX:XX
wlan1: send auth to XX:XX:XX:XX:XX:XX (try 1/3)
wlan1: send auth to XX:XX:XX:XX:XX:XX (try 2/3)
wlan1: send auth to XX:XX:XX:XX:XX:XX (try 3/3)
wlan1: authentication with XX:XX:XX:XX:XX:XX timed out

Using another wifi adapter in monitor mode I see this (GLTechno_XX:XX:XX is the AP using QCA9887; Tp-LinkT_YY:YY:YY is the STA using the MT7610E):

2965	596.801882973	Tp-LinkT_YY:YY:YY	Broadcast		802.11	119	Probe Request, SN=6, FN=0, Flags=........, SSID=TEST
2966	596.802178823	GLTechno_XX:XX:XX	Broadcast		802.11	229	Beacon frame, SN=1006, FN=0, Flags=........, BI=200, SSID=TEST
2967	596.802965303	GLTechno_XX:XX:XX	Tp-LinkT_YY:YY:YY	802.11	223	Probe Response, SN=1007, FN=0, Flags=........, BI=200, SSID=TEST
2968	596.803290283	GLTechno_XX:XX:XX	Tp-LinkT_YY:YY:YY	802.11	223	Probe Response, SN=1007, FN=0, Flags=....R..., BI=200, SSID=TEST
2969	596.803619383	GLTechno_XX:XX:XX	Tp-LinkT_YY:YY:YY	802.11	223	Probe Response, SN=1007, FN=0, Flags=....R..., BI=200, SSID=TEST
2970	596.803952793	GLTechno_XX:XX:XX	Tp-LinkT_YY:YY:YY	802.11	223	Probe Response, SN=1007, FN=0, Flags=....R..., BI=200, SSID=TEST
2971	597.006971814	GLTechno_XX:XX:XX	Broadcast		802.11	229	Beacon frame, SN=1008, FN=0, Flags=........, BI=200, SSID=TEST
2972	597.188437285	Tp-LinkT_YY:YY:YY	Broadcast		802.11	119	Probe Request, SN=32, FN=0, Flags=........, SSID=TEST
2973	597.189427945	GLTechno_XX:XX:XX	Tp-LinkT_YY:YY:YY	802.11	223	Probe Response, SN=1009, FN=0, Flags=........, BI=200, SSID=TEST
2974	597.189778145	GLTechno_XX:XX:XX	Tp-LinkT_YY:YY:YY	802.11	223	Probe Response, SN=1009, FN=0, Flags=....R..., BI=200, SSID=TEST
2975	597.190191515	GLTechno_XX:XX:XX	Tp-LinkT_YY:YY:YY	802.11	223	Probe Response, SN=1009, FN=0, Flags=....R..., BI=200, SSID=TEST
2976	597.190488715	GLTechno_XX:XX:XX	Tp-LinkT_YY:YY:YY	802.11	223	Probe Response, SN=1009, FN=0, Flags=....R..., BI=200, SSID=TEST
2977	597.211754664	GLTechno_XX:XX:XX	Broadcast		802.11	229	Beacon frame, SN=1010, FN=0, Flags=........, BI=200, SSID=TEST

The MT7610E seems to not send any authentication packet after the Probe Response. However if you look closely, the SN of the TP-LINK jumps from 6 to 32, so I think that router at least creates the packets but for some reason it's not able to transmit to the world.

Additional infos:
1) When I restart the MT7610E I usually get this message

[ 1315.597177] mt76x0e 0000:01:00.0: TX DMA did not stop
[ 1321.598430] mt76x0e 0000:01:00.0: Warning: MAC TX did not stop!

and some packets are sent immediately after the second message. Probably there is an issue with the queues?

2) Rarely I am able to connect to the AP but only when I start two interfaces on the same MT7610E (one in STA and another in Monitor mode). Maybe the delay added by the second interface fixes something?

3) Interestingly MT7610U connected to the USB port of the same router works correctly, so the problem seems to be specific to the MT7610E.

Am I the only one with this problem? I tried to find the problem in the MT7610E specific part of the driver but it's too complex for me. I need at least some hints from the devs to narrow the search.

Thank you.

Start with the MT7610E-specific driver path and trace the STA authentication flow after the AP's Probe Response, then inspect the reported TX DMA and MAC TX stop warnings. Reproduce with the TP-LINK TL-WR902AC or ASUS RT-AC51U and compare against the working MT7610U. Done means the MT7610E authenticates reliably in STA mode without requiring a monitor interface.