I've got a Mac OS 26 guest running on Mac OS 26 host. The guest has Sharing > Share Custom Mac Folders With Macos enabled. When an app in the guest accesses a text file via "My Shared Files", it appears that the guest caches the contents of that file and doesn't invalidate the cache when it gets changed on the host -- that is, the guest doesn't see changes to the text file until the guest restarts. If the guest accesses host files using Network and shared network folders, then the guest sees the most recent version of the host files, as expected. Is this a bug?
