Thread:Project:Support desk/Widget:Google Spreadsheet refused/reply (3)

The problem isn't your MediaWiki installation.

Manual:$wgBreakFrames and Manual:$wgApiFrameOptions etc won't help you, since that controls whether to allow your wiki to be inserted inside another page in a frame. But this is different. That's about inserting google spreadsheets inside your MediaWiki.

If you take a closer look, you'll see that your iframe widget is using one URL for the spreadsheet, while the google spreadsheet widget is using a different one. Editing how it constructs the URL in so it's the same as the iframe that works would solve the issue.