Is it possible to clean checkout directory for all snapshot dependencies in a Trigger Schedule ?

I have a tigger that is schedule to run daily on a specifc time .
It has several snapshot depenedencies .

I have tried the advanced options of the Trigger , and enabled  "Clean all files in checkout directory before build."  option .

But when I examine the build logs of each of the dependent builds there were triggered , I do not see  checkout directory being cleaned.

Please help.

Thanks in advance.