In my hit data (clickstream) I have some page views to a url that have a visit_page_num of 0. How can that happen? Also, our website is sending in that the code_ver is JS-2.9.0-LCUM. The visit_page_num=0 hits are sending in a code_ver of TA-1.0.?

While I don't know offhand what the TA-1.0 version is, maybe if you can identify where the tracking is coming from you can get some more info... is it maybe coming from a very old code implementation? Maybe a no-script implementation (which might explain the lack of hit depth counter) like for a Newletter tracking, or as a compensation for users who have disabled JS? Maybe it's an AMP implementation?

There's several possibilities, I think the first step is to try and find the page that is sending this tracking call, then to investigate how the code has been implemented.

Good luck.

Check hit_source in your data source to understand where the hit is coming from. Also check exclude_hit to make sure the hit is not exlucded.

Just by what you described I would guess the hits with visit_page_num=0 would be stitched data from target using A4T integration so that would make sense that the page count is not increased or used as these hits would be stitched to other analytics hit.