welcome to the forum,
tl;dr - need to use a debug log and look for issues.
check out my summary for the two rclone vfs caches
can remove that flag, does nothing on rclone mount
can remove that flag. that is for the deprecated cache remote, which you are not using.
that is for the vfs dir cache, not the vfs file cache.
so should not affect downloading, uploading, streaming.
if a cached file is open, in-use, lock, then rclone will not remove it.
as compared to which other sftp copy tools?