Is there any error message you are seeing while completing the process? As this may have multiple causes, any information displayed while the behavior is occurring may guide us in identifying the cause.
In the meantime, you can read about Cloud SQL quotas and limits [1] and best practices [2].
[1] https://cloud.google.com/sql/docs/quotas
[2] https://cloud.google.com/sql/docs/mysql/import-export