When uploading a scorm package from Captivate 2019 (22.214.171.1246) to client LMS, the file opens with a white screen with a buffer wheel and doesn't go any further. However, it works fine with no error when tested in Adobe Scorm Cloud and preview in web browsers (Mac Safari, Mac Chrome).
I'm using Captivate 2019 (126.96.36.1996) on macOS Catalina v10.15.7.
Check with the Administrator of the LMS web server to find out if the server is configured to allow JSON files. That is the usual reason for the issue you describe. SCORM Cloud does allow JSON, so it doesn't have this problem.