If they show up for any length of time I mark them present for that half of the day. I have a few kids who are effectively absent every day but log in and at least attempt to join, they just have crappy internet.
I’m also supposed to contact parents if they miss more than 2 days in a row, but my class is huge and I just... don’t. I have a few I need to contact because they’re not usually absent. But otherwise... I have the same 3 or 4 kids gone daily and I know why they’re gone and nagging parents doesn’t make any difference, so I mark them absent and move on. 2 have terrible internet, 1 just doesn’t care to come (though he does show up long enough for me to mark him present), and one’s mom is 100% done with remote learning and she just gets mad when I text.
sorry, ranting. But yeah. If they show up, I mark them present.