Mat doc show 2 line item with 1 TR created but only 1 line show TO confirm & line 2 interim issue

Hi, SAP expect
Would like to seek your expertise on below issue.

Material document posted for 2 line material with 1 TR created.
issue
TR display screen show
line item 1 TO auto confirm/ process

line item 2 did not show TO auto confirm and show at 921 interim stock.

would like to ask the SAP expect on what possibility scenario will cause 1 of the line item in TR fail to confirm TO creation?