Whenever you add columns to a table and want to adjust the length of a column, the more columns you add the further the "blue line" that you can drag to adjust a column's length becomes dislocated (moves further to the right by one pixel per column), to the point of no longer being able to click on it (when you have around 13+ columns), thus making the column length impossible to adjust. This happens on every single table you make, regardless of the number of rows it may have.
I'm using Windows 10 by the way