@gigaday Thanks for the information. That works perfectly. It's not a great solution, but at least it is good for now until the issue is corrected.

@leocg As noted in the OP, two to three days ago, before the update, everything was working perfectly and I could see what was in my Dropbox folders. So, "disabling ad and tracking blockers, as well as all extensions" makes no sense considering that they were, and are, not the problem. More so, I haven't added or changed anything.

Two days ago, everything was fine when I went into my Dropbox account. Folders and files could be accessed without issue. But the most recent update did something and now I can not see any of my files in the folders. I've reported the issue to Dropbox, but it looks more like an Opera browser issue since I can see everything perfectly fine when I go into DB with Microsoft Edge. I haven't made any changes to Opera for awhile, so it has to be the latest update.

Though this topic is old, I'd like to say that I second this idea since the Stylish expansion add-on gives users this option for Firefox and it is extremely helpful.