Hi. Did someone by any chance duplicate the board and move the duplicate to a private workspace, or make the duplicated board private? I have recently had this issue where I duplicated a board which had a connection, and moved it to a private workspace. That in effect meant that there were two sets of data connected to that column - one from the original connection, and one from the duplicated one in the private workspace. Because some of that data was private, it made the column disappear for everyone on the original board. I was the only one who could see it, because the private workspace I’d moved the duplicate board to was mine - only I had access.
Unfortunately, in your position, there is no good way to tell whether someone has done this except ask around. Because they are the only person who can rectify it.
If you can identify them, they can fix it by going to the board where the connected column is (the one you can no longer see, but they should be able to), and going to Settings > Customise Connect Board column. That should show that TWO boards are connected: the one it’s meant to be connected to, and the duplicated board. They just need to hit disconnect for the duplicated board (make sure they choose the right one because this action is irreversible). Then when you hit refresh, it should (hopefully) be back. It might take an hour or so to reappear, because that’s what happened to us.
Just a hunch, but this is one possible explanation.
https://community.monday.com/t/two-way-connection-column-disappeared/37171