@Solari For context, there are three types of issues with dynamically-sized embeds like Twitter's:
- The tweet is entirely blank.
- The tweet is displayed but not redimensioned at all.
- The tweet is displayed and redimensioned, but it's slightly off.
In the past, I've had some issues with calculating the correct height of a tweet across browsers because of inconsistencies in their implementation. Nowadays, I think the method I use works consistently on all modern browsers. That solves the third type above, which leaves the first two.
If a tweet is entirely blank, the likeliest explanation is that it's being blocked by an extension or a built-in adblocker. Firefox's "Tracking Protection" feature blocks content from Amazon and may interfere with other embeds too, although it does not currently block Twitter based on what I see here. The solution is usually to whitelist the current website or disable the extension for the relevant domains. As mentioned above, some automated content blockers are going overboard and blocking more than just ads and trackers.
If a tweet is not redimensioned (which is the case here) then it's a JavaScript issue. It could be that JavaScript is disabled for the current website/domain or that an extension prevents JavaScript from setting the tweet to its correct height. If possible, ask the user to check out their browser's developer console (the keyboard shortcut in Chrome and Firefox is usually Ctrl+Shift+J) and copy/paste all of the error messages. If they have any extensions installed, ask them to disable them and see if it changes anything.
You can also ask them to check out
this test page and see if the tweet is displayed correctly on its own. If it's not, check out the developer console for errors.