Fear of scope creep, Risk of any major changes
Fixed price projects means fixed scope. Every fixed scope associate with fixed milestones. And so there is a minimal scope for adopting any change requests. Changes which are under scope and which can easily be accommodated are only accepted.In such a case it minimizes agile principles to adopt changes. This is one of the important shortfall of agile in fixed price project.
Focus on quick delivery.
In a fixed price project delivery always takes first seat irrespective of any processes or frameworks to meet the predefined project milestones and meet the budget. So balance of self organized team reduces and hence puts more pressure on delivery team , which compromises quality of the product.
In a fixed price project agile principles always takes the back seat as more focus towards end delivery due to budget constraint.More technical team are added to development team and almost zero inclination towards practicing agile. Delivery manager plays a crucial role and not scrum master in such a situation.