Left block category sort order (PS 1.6.0.9)

[bsdll]

I have a strange problem with the display order of the categories in the category block.

 

If I go into the category and change the sort order of the sub-categories by dragging them, then refresh the page on the frontend then they will be in the correct positions in both the category block and the parent category page.

 

If I go into the database and simulate the change (modify the position in ps_category_shop), they will be in the correct order on the parent category page but they will not change order in the category block. Nothing I can see will make the category block refresh its list of categories.

 

Is there something else that the drag and drop does that is not stored in the database? And if it's a remembering thing, how long will it remember for before it reloads from the database?