No in theory it shouldn’t.
Over the years there has been some debate on how a contractor, who is not employed by one company, be assessed.
In practice the main challenge was that some assessors who were employed by a company were reluctant to assess someone they did not know; and; who would not be a regular member of their team.
The industry has addressed this issue, and the availability of transferable, independent certificates of competence has reduced this. Many agencies have been proactive and supported contractors in their professional development. This includes providing evidence such as witness testimonials, that can be used by the contractor.