Moving from Lightroom to Classic issue

I wanted to create a lightroom book and moved from lightroom CC to classic.

In the process of synchronising the pictures, i realised my hard drive was getting full as it duplicated all pictures in the 2 lightroom version and changed the saving folder to my NAS. 

While it was resynchronising, I noticed my pictures where being replaced by older ones, overwriting all the pictures i had already edited.

Even weirder, i kept the edit of the pictures but on an older pictures.

I tried to check if the same thing was happening on the cloud

What should i do?

I see an option to delete all synched photos? Would that help?