Batch convert jpg to graytone jpg's

I am trying to run a batch conversion of 560 jpgs to graytone and only seem to have a limited success. The process with run for 60 or so images then stop and say it is done. Can someone either share a workflow that does this perhaps or try and talk me through the steps needed.

I have tried selected the images then copying them and running the colour change to graytone. This works but not for all the files. I am a bit lost as to where to go next. I don't want to do it by hand! All help much appreciated.

I have attached a snapshot of one of the methods I have tried so far and this works as the others for perhaps 60 or so images.

I have confirmed that Apply ColorSync Profile to Images crashes after a number of iterations, on my system its 103 photos.

Workaround only run the script on smaller batches of photos.

or use

Apply Quartz Composition Filter to Image Files > Black and White