This is the third time this has happened. I've been using my main page all day, but after toggling to another board and then back to my main board all the bookmark widgets were stuffed down the left column.

Interestingly, the grid was also removed. I've not made any changes to any page settings or individual bookmark widget settings, just clicking the buttons to open pages.

This time I have some screenshots showing what happened. I made a duplicate copy of my main page after the last time, and here is both the before and after where the board moved all the widgets automatically.