Sync subdirectories recursively excluding some

Hi Everyone… just tried RClone for the first time. Read for about 20 mins but could not get it straight.

I have a deep directory structure with 1000s of images inside 100s of subdirectories to be sync’d recursively to my Google Drive, but leaving out ./cache and ./thumbnails directory.

Issue #1 rClone does not copy subdirectories

rclone sync /synctest/images GDrive:/images
this … only sync files in the dir specified
Why is it not sync’ng and creating the directory structure ? What arguments need to be passed to sync all subdir recursive?

issue #2 How to exclude certain directories

is this right ?
rclone sync /synctest/images GDrive:/images --exclude "/thumbnails/**"

I read you can make and load and exclusion file… but if I only need to exclude one or two directories, what will be the right parameter to pass ?