This seems to affect the recent version of Opera released within the past day, as I can no longer see any visible posts on the Full-Page Shoutbox.
If anyone else uses this iteration of Opera and is wondering what the root cause is, the update is likely the cause of no longer seeing any shoutbox posts.

Could you double-check and make sure no JavaScript is being blocked on the page?
If that's not the issue, could you please clarify which specific version of Opera this is? And are you able to try other browsers to make sure it is a browser-related issue and not an issue with your account?
🐝 ☕ bug (he/him) | your friendly neighborhood code wrangler. stay in the loop! join and check out the latest admin post highlights
Update Your version 67.0.3575.115 of current Opera Browser
This happened after the current update occurred on March 31st of 2020
I never changed any of the setting of the browser and always ensure that java is running on this site.
I can access the browser just fine with a previous version of Opera as I use a portable version from time to time and also the version of Opera GX allows the shoutbox as well. As do other browsers like Chrome etc.

Shoutbox still blank for you on Opera?
I had to change to a different version of Opera, which I now use Opera GX, I'm uncertain if the standard version of Opera still has the issue but I don't currently have the issues with this iteration of Opera.
It may have been a cache issue or something to do with a update since the browser seemed to work again after a new update was created for GX.
