dts are zeros at the start

Hi folks,

Always when I catch up a live rtmp stream I am getting zero DTS's on the start.

ffprobe -rtmp_live live -i "rtmp://ams/live/stream" -read_intervals %+0.2 -show_entries packet=dts | findstr dts

dts=0

dts=0

dts=0

dts=0

... skipped repeating dts=0

dts=0

dts=0

dts=0

dts=23

dts=31

dts=46

dts=69

dts=71

dts=93

dts=111

dts=116

dts=139

How could I fix this?