He was most likely in his office, negotiating with Little Lindsey Graham and his fellow Democrats.
When they began logging the votes, I could see Graham in a seat on the far side of the floor - when the camera angle was past the people logging the votes.. I can’t say which direction except if you were looking at the well of the Senate from the front, to the left of that. All during those hours, there was a huddle of people right at the spot where Graham was but difficult to see him as the screen ticker was in the way. I could see some white hair on the person sitting and I believe he was sitting there the whole evening. I wish they would be made to sit in their assigned seats and record their votes from there. They behave like 2nd graders so let’s treat them as such.
Watch enough of these stupid votes and you can i.d. people on the floor easily. Amazed at how many women were dressed in pants - not a skirt in sight! Feinstein easy to spot - Warren - easy to spot, same with Sanders, Flake, Rubio - and on and on... Some pretty beefy women there! LOL