Dos your line manager understand what objectives are? They are not about doing ridiculous hours to prove yourself they are supposed to be about doing your job possibly with some stretch I.e. development.
This is what CIPD says
Objectives or goals are a powerful motivating tool that helps improve performance. They can be expressed as KPIs, ongoing quality standards or tasks to be completed by specified dates. In either case, they should be based on a full understanding of what constitutes good performance (see above).
Employees must be bought into and committed to their objectives for them to be effective. But contrary to popular opinion, it is not generally better for employees to set their own goals.
Usually, objectives are most effective if they centre on specific outcomes and are stretching. This is often described as ‘SMART’ (typically, Specific, Measurable, Achievable, Relevant, and Time-bound). However, research shows that this is not always the case. For complex tasks – for example, which involve analysing information before making decisions and acting – it’s usually better to focus on learning outcomes (how you will improve or develop), or even vaguer objectives to ‘do one’s best’. And for jobs that are heavily reliant on teamwork, it can be more effective to focus objectives on behaviours.
Performance can be defined at an individual, a team level, or a mixture of both. Where collaboration is important in carrying out tasks, or responsibility for results is shared, it makes sense to focus on team performance. If striking a balance between individual and team objectives, employers should be careful that they do not undermine each other.
You need to think about applying for jobs as it sounds like you have reached the point where the job is not giving you anything back.