PowerProtect Cloud Snapshot Manager REST API

I've been using the PowerProtect CSM REST API since the beginning of this year. But a Python script that I wrote, has stopped working when using the /csm/v2/plans/{plan-id}/runs path with the parameters of start_time_from or start_time_to.

Would anybody be able to shed some light on why the API isn't behaving as documented?

https://developer.dell.com/apis/5788/versions/latest/api/protection-plans-v2.yaml/paths/~1v2~1plans~1%7Bplan_id%7D~1runs/get