We have some tables with a couple hundred fields. In order to export records I need to have layouts with all the fields available. When setting up a table layout, I try to select all the fields, but only the first half or so will get into the layout. I haven't manually counted to see if there is a magic number at which it seems to cutoff, but it seems to be a hundred or so. Then when I try to select additional fields, sometimes it allows me to grab one or two more, but not the rest.