Are you using sepaate images for each frame or a single image across multiple frames?
Can you post a zipped version of the project file for others to check and see what the issue is?
Thanks for your reply, sorry can't really post it as it's a commercial project. They are 2 separate images, which become visible / hidden alternately to show each one after the other.
I've sort of solved my problem by just repeating this manually for now but would still be interested to know if looping is possible - however appreciate this may be tricky without the file.
Could you just post a sample file where you use the simple same structure with sample images so we can see what you are doing?
Otherwise a way to do it could be to have sym.play(0); at the end (loops back to first frame) and play(); at the beginnning so t starts again.