It's been suggested it's because of a bug I don't have job chaining options available as I've already prestiged jobs and I've done educations (not pr yet)... Please help

Could you post a screenshot of your jobs page please? 

You need to be at 100% of a job to choose chaining as the next track. Just because you have prestiged in the past doesn't just give you the ability to chain as it is a separate path/skill.