Revert "fix a bug which prevented thumbnail generation in some cases"

This reverts commit 7f5eb7f10a1336a75c0775052b308e26457bf10a.
Revert "added an option to use cache or not and added actions based on the presence or absence of all thumbnails vs single thumbnail"

This reverts commit 912e6d41d0e2269d64653eff15b68eb5125c6565.