adgbu over the past few replies it seems people have been blinded by this mess and not read the post they’re commenting to in full. If you have the old root location set to a different drive, that’s where the cache resides too, just not visible by folder size because duh, cache is French for hidden and so it doesn’t count. If you don’t see the numbers lining up and want reassurance, log out of your account in the OneDrive client, it’ll spend some time remaking the cache into actual files in the location on the external drive. Then log back in and select that location for the OneDrive folder (so, the parent folder where you want the OneDrive folder to reside), then you’ll be sure that the cache is there.
To be clear, I don’t work for Microsoft and I’m also upset by this, but rote lamentations that do not take into account the original post and related updates don’t really help.