This may be due to hitting your perspective limit.
If you receive an error when trying to post a new perspective using the API and your schema looks correct, make sure to check if you are at the maximum amount of active perspectives. If you are at your limit you will need to set the line that includes the perspective in reports to “false."
"include_in_reports": "false”
After making this correction it should allow you to post your perspective. You will then need to decide which perspective to remove from being active in order to turn your newly created perspective to active which can be done through the UI or API.