Hi RohitBah,
I tried to deploy some tests to better investigate the scenario you are facing, but it seems like the linked file path is not same as yours. May I confirm if all workbooks are saved in a SharePoint site with document folders naming August and September? Please correct me if I'm in the wrong way.
Meanwhile, I have opened the private message channel for you and give it a try if you can successfully upload images from there so that we can troubleshoot this scenario more efficiently to save your time. Click: Private Messages - Microsoft Community
Best Regards,
Mia