Unable to receive OUT packet on USB in device mode

Hello,

I am trying to use USB on Cyclone V soc with tinyUSB. I am able to receive SETUP transaction and send device descriptor, but then I cannot receive and acknowledge the next OUT transaction.

I see that DOEPINT0.nakintrpt goes to 1, confirming that the device responds NAK to the OUT transaction, but I don't understand why. Here are the settings that are relevant to me :
GAHBCFG.dmaen = 0
DCTL.sgoutnak = 1
GRXFSIZ.rxfdep = 0x50
DOEPMSK.xfercomplmsk = 1
GINTMSK.rxflvlmsk = 1

Written before waiting for OUT packet:
DOEPCTL0.epena = 1
DOEPCTL0.cnak = 1
DOEPTSIZ0.xfersize = 0
DOEPTSIZ0.pktcnt = 1

I am lacking ideas of where to search or what could cause this behaviour. Is there anything to take care ?

Best regards,

Romain