In the right hand bar for Columns in Table options, the hidden columns are sorted alphabetically. When creating a filter, however, the columns have no logical sort. Looks like they are sorted by creation date of the columns. Similarly when viewing the popup expanded view, under hidden columns they are sorted in the same way as for the filters.
I am suggesting that these are either: A) Sorted Alphabetically, or B) Sorted based on where the columns appear on the main table.