Bustycat Sorry to burst your bubble, but I'm running v22.022.0130.0001 an Insider Edition and apart from a slightly different UI the core sync functionality is exactly the same - extremely buggy, I have 600Gb and >350k files and the file provider API crashes multiple times daily, no PERSISTENT offline files, and semi-working auto-save. Just awful.!!!
I will say that to get the subfolder size sit on an unexpanded folder and press OPTION 'right arrow', but as said, this only works initially. Any changes to files or folders under the root folder revert back to 'Files On Demand' (cloud only). So incredibly frustrating.
Frankly this is an appealing situation and HUGELY disruptive for everyone, I can only put it down to extreme arrogance that the MS team has gone silent, they have not even addressed the offline files issue we are all so upset about either. Very disappointing.!!!
The windows version is fine too, so I assume Mac users are the guinea pigs for this 'wonderful and exciting experience'.