I am on the same boat.
Applied H1-B Extension on Sept 19th 2019 at Nebraska center after Dec 31st 2019 transferred to Vermont center without RFE case was approved on Mar 10th 2020. Unfortunately my case was approved on heart of covid-19 and my I-797 copy courier service missed some where. Raised the Service Request with USCIS response back apply duplicate copy request. But for I-824 duplicate copy it has long queue i.e. 7-12 months. My Employer is saying if copy is not received before I94 expiry + 240 days i can't work and out of payroll.
Please help if any suggestions or alternatives to get the atleast soft copies from USICS.