Ah, the screenshot explains the issue: It seems the website (Facebook?) is blocking EVAL on its website, just like Github. This problem is not related to OnDownload, but to storeEval.
For a workaround see 'unsafe-eval' is not an allowed source of script - #2 by ulrich - UI.Vision RPA - UI.Vision RPA Software Forum | Discuss RPA Automation, Selenium IDE and OCR API Text Recognition