tested timeshift on a ext4 secure harddrive with password , so that is a harddrive that you can not enter without a password.
so i have put timeshift over there , and have try that out and i must say it works perfect , i even have do some deleting stuff on my computer and the timeshift have put it all back , very good tool , it makes very day another back up , so if something dont work good anymore , just open timeshift and place that last image back perfect...
(https://thumb.ibb.co/iUBzYz/Schermafdruk_2018_08_08_06_13_13.png)(https://preview.ibb.co/b2e8RK/Schermafdruk_2018_08_08_06_13_13.png)link -> https://ibb.co/iUBzYz