(Everything 1.4.1 and Opus beta .35)
Tried out the 'calculate folder sizes with everything' option, but it's producing wildly incorrect results. As you drill down the tree the sub-totals get more correct, but these values are not propagating back up the tree...and it's not jsut e.g. cloud folders, but any normal folder too.
(If I switch back to traditional Opus folder sizes it works correctly, albeit much more slowly - and I have asked Everything to rebuild the cache...)
Do you have Everything configured to index all files/folders or could it be excluding some?
With OneDrive, there may also be differences in whether offline files are included in the counts or not.
I do have Everything set to index all local drives, and a bunch of NTFS shares too. But this affects local drives, from the drive level down. It's definitely not just cloud folders (which I have to set to sync everything locally too).
With Beta 44 still seeing problems with folder sizes quite regularly. Across multiple machines, including a new main PC at home with a very vanilla set-up.
Can't be the only one, surely?
Opus, or Everything - it doesn't seem to matter which is calculating them, there are errors with both.
With Opus, this is e.g. a libraries view (of a bunch of network folders) - and all of these folders have GB of files in them. The wrong ones always show 4KB. These are folders on network drives, so nothing out the ordinary or cloud related here.
With Everything, even with plain local drives, with no exclusions in Everything, the sizes it calculates are routinely wildly inaccurate.
Opus seems to get those mostly right, at least.
I'm going to end up deleting a folder I think is empty one day, when it in fact is not...
Do the folder sizes show up correctly in an Everything window?
That's a good question - they seem to be correct in Everything itself:
But wrong in Opus with Everything calculation turned on (libraries view):
Which doesn't surprise me as Opus is also reporting these wrong when it's the one calculating them (again in libraries view). It appears when I go via Network, rather than libraries, Opus gets them right.
Hitting 'F5' to update the listing doesn't fix thing - indeed, it often makes things worse, with more things r being shown as '4kb' in size.
It's not just the libraries view, though - the original example I posted above is just a local drive and it's absolutely repeatable - if I change to Everything, the sizes are wrong instantly -
Although on this occasion it IS wrong in Everything:
So...it's thoroughly broken, that's for sure.
Opus itself is vastly slower with the calculcation (even with screamingly vast local NVMe drives, if you have a large collection, it takes 10 to 20 seconds to get there...)...but overall is at least a bit more reliable - and there using 'F5' to update the listing does seem ultimately result in correct sizes being shown.
But there's definitely something not right here generally (again, multiple machines, and I have tried in two different locations on two different networks to be sure - it's not machine/setup specific).
You can get a second opinion with this script column. It gets the folder size through the Everything command line whereas Opus uses the SDK. It also allows you to use Everything 1.5.
Network folders in libraries are out of the ordinary. 
Windows doesn't really support that, although it also doesn't actively prevent it.
That combination also definitely complicate things in terms of Everything folder sizes, since Everything may know the network path but not the library path, or vice versa. Or it may not know either path. I'm not sure of the details of what it indexes and what Opus would ask it about in that situation, but it's definitely going to be a special case. Something we need to look at in more detail when we get a chance.
But it sounded like you were seeing issues with other cases as well?
