"calculate all sizes" is grayed out in finder window view options

[jj5406]

I was remotely helping my daughter to figure out what is eating up all of the space on her disk (particularly the large amount marked as "system data"), while simultaneously doing the same operations on my Mac. When I told her to check the "calculate all sizes" box in the "view options" window, on her computer that box was grayed out and unchangeable. She was in list view (I think otherwise that option is not even shown). She says she is running Sonoma 14.0 (I guess I'd better have her update her OS - I am running 14.7.1). I guess it could be a bug in the initial release of Sonoma, but if it's not that, is there some other reason this feature would be inaccessible? Thanks.