Getting #value! when converting date

You have strings that are dd/mm/yyyy instead of the expected mm/dd/yyyy.

Use this in B1, and copy down:

=DATE(RIGHT(A1,4),MID(A1,FIND("/",A1)+1,FIND("/",A1,FIND("/",A1)+1)-FIND("/",A1)-1),LEFT(A1,FIND("/",A1)-1))

This can be simplified if you always have two digit days and two digit months:

=DATE(RIGHT(A1,4),MID(A1,4,2),LEFT(A1,2))

Likely because your system date is set to mm/dd/yyyy.

Hence, 12/10/17 will evaluate to Dec 10 2017.

But it looks like texts are in dd/mm/yyyy format.
Try below formula.
=DATE(RIGHT(A1,4),MID(A1,4,2),LEFT(A1,2))

Note that above will not work if you have d/m/yyyy text in column A (ex: 13/1/2017).

In that case you'll need additional calculation steps.