First off, a general suggestion...when troubleshooting it might help to include the software/OS version you're working onâ€”it could help if the problem is version-specific. That said, I'm not a web designer and don't use Dreamweaver, but after a couple of searches I found a couple of items (keep in mind I don't know what your level of expertise is in general or in Dreamweaver)..
- Apparently disappearing elements in Split View is not an unheard-of problemâ€”Adobe claims to a fixed a similar issue a few years back
- Another possibility might be related to code errors?
- Apparently Dreamweaver's Design View won't show code with table structure errors
- One suggestion was to "click on the red cross icon on the status bar and...open..up the Output panel to show...HTML errors"; supposedly repairing these errors (which may not have prevented the browser from displaying the table) should restore the display
That's about all I can offer, but I've linked this thread to one of our Dreamweaver courses (above)â€”it's an older course, but perhaps the course author will still be available to respond, and maybe have some further advice or suggestions..