There are a couple of Response Headers coming from elwoodtest.erecruitcloud.com that are important (see attached image)
Referrer-Policy: strict-origin-when-cross-origin – this says if you have a https:// url specified in the web window that you need to also have the course or web page served from https:// as well. If you serve the course from http:// … then the web window will not load.
X-Frame-Options: SAMEORIGIN – this says that any course or webpage has to be from https://elwoodtest.erecruitcloud.com in order for for it to load an iframe with the content from https://elwoodtest.erecruitcloud.com/
Basically if you want your course to be taken at https://mylms.com/mycourse1 then you need to have the administrator for the server that hosts https://elwoodtest.erecruitcloud.com set the X-Frame-Options in the server response headers to allow it to be in a frame on your lms’ server.
Hope that help, it’s a little confusing but it’s pretty common to have these issues nowadays because of clickjacking security concerns.