I can see nmea port is enabled, did you see modem port and DM port?
Btw, which firmware are you using?
I don’t see problem with FW R17:
root@fx30:~# ls /dev/nmea
/dev/nmea
root@fx30:~# cm info
Device: WP7605
IMEI: 353532100012345
IMEISV: F
FSN: 2A917285012345
Firmware Version: SWI9X07Y_03.00.13.00 9f157c jenkins 2021/07/27 04:04:43
Bootloader Version: SWI9X07Y_03.00.13.00 9f157c jenkins 2021/07/27 04:04:43
MCU Version:
PRI Part Number (PN): 9908705
PRI Revision: 002.010
Carrier PRI Name: GENERIC
Carrier PRI Revision: 002.109_000
SKU: 1104208
Last Reset Cause: Power Down
Resets Count: Expected: 262 Unexpected: 0
root@fx30:~# legato version
21.05.2.rc2_7f59219499ecf02274c4ac7575e4f8c5_modified
root@fx30:~# ^C
root@fx30:~# cat /dev/nmea
$GPVTG,,T,,M,,N,,K,N*2C
$GNVTG,,T,,M,,N,,K,N*32
$GPGGA,,,,,,0,,,,,,,,*66
$PQXFI,,,,,,,,,*7A
$GPRMC,,V,,,,,,,,,,N,*7F
$GNRMC,,V,,,,,,,,,,N,*61
$GPGSA,A,1,,,,,,,,,,,,,,,,*32
$GPGRS,,,,,,,,,,,,*51
$GPGLL,,,,,,V,N*64
$GPGGA,,,,,,0,,,,,,,,*66
$PQXFI,,,,,,,,,*7A
$GPRMC,,V,,,,,,,,,,N,*7F