I have an issue whereby I add items to calculation a variation on a project, but the displayed rate for an item will change from the original schedule of rates. i.e. The installation of a grille was at £13.90 on the original schedule and original file, but when adding grilles they came out at £14.63. All other rates also changed, some up, some down. It's an archived file and I also tried fixing the item prices in the "distribute costs" tab of the estimate summary.

Does anybody have a solution or know why this may be happening?