INDD exporting into black and white jpg

I'm having the weirdest issue and I hope someone can help.

When I export a colour indd to a jpg, the jpg is in black and white instead of colour. I've spent an hour testing and if I export the indd into a PDF or PNG the colour is fine so it seems like jpg is the only form affected.

This is even more strange because I have exported this same indd into a jpg 2 days ago and the colour was not affected. I've restarted the program etc, but nothing seems to help and I can't find anyone else who has had this previous issue.

Any help is greatly appreciated as this is a work project that needs to get done ASAP and I'm a hopeless beginner with InDesign....