PF10 in atmel ATxmegaxxxA1U
Looks like a typo. In conf_isp.h the ISP port pin is defined as 0, not 10.

// Definition of hardware condition to enter in ISP mode
#if XMEGA_A1
# define ISP_PORT_DIR      PORTF_DIR
# define ISP_PORT_PINCTRL  PORTF_PIN5CTRL
# define ISP_PORT_IN       PORTF_IN
# define ISP_PORT_PIN      0


ETA: 
But even that doesn't match the pinout diagram in the datasheet, which says PDI_DATA = PORT Q pin 89. This is the pin used on the MT-X1S ATxmega128a1(u)dev board by Mattairtech.

I have no idea how it is supposed to work when the source code references a different pin. We can only hope that the actual firmware supplied in the chips is correct...