Run Script After Sandbox Creation and Refresh

I had the same issue and raised a ticket for Salesforce support team.

They came back saying there is a bug at their end and they are working on fixing it. Fix is expected to be available by end of next week (safe harbor).

Here is the response I got from Salesforce Support team.

Hi Arpit,

Hope you are doing good.

I would like to inform you that our R&D team has identified this issue as a bug and are working on it to fix the same. I'll keep you posted of further updates on this one.

Regards
Ayush Sodhi
Success Agent- Tier 2