Grep Mac verse Windows

Morning, I've had a weird thing happen today.

Currently I work in indesign on a Mac. On one of the projects I've worked on I created grep styles to help speed up the formatting process. The project these greps applied too has since moved back into the customers hands for formatting. They work in indesign but on a PC platform. Today I was trying to show them how to use the Greps I've created for this particular project. But they did not work. I tested the Greps before I left to make sure all was above board before teaching the client. But nothing happened when I ran the find and change. Nothing was being found to change. Has anyone else experienced this? Is there a different find and change language from PC to MAC. I assumed that Greps were a universal language and can be used on both platforms but that isn't the case from what I've just experienced.

Does anyone have an answer or suggestion to help get my Grep styles to work on both platforms?