Question about NULL in position_data4

Hi!

I have a question about getting NULL values in position_data4. The data contains value in "rawmsg" but the corresponding "lat", "lon", and "alt" values are NULL. I'm wondering what would be the cause of that. I tried using the message provided in "rawmsg" and it can be decoded and also can pass the CRC check. I'm curious why the "lat", "lon", and "alt" are marked as NULL.

Here's an example:
=11.0ptrawmsg                                                    mintime                              icao24          hcr      =11.0ptnic     lat          lon        alt        groundspeed=11.0pt    gsresolution=11.0pt    heading
8facb89c5937664328c9a104fcd0       12/1/2022  11:40:19 PM        acb89c     185.2         9     NULL   NULL    NULL             NULL             NULL      NULL

Thanks!