When this happens, the contraption will cease to work.
This latter dialog box will not display a progress bar. This will cause an "Export in progress" progress bar to appear, followed by and "Initializing upload" dialog box. Select the world that you downloaded in Step 3 and noted in Step 4.It may also be advisable to avoid consuming significant bandwidth on other devices on the network, e.g., streaming videos, downloading files, etc. Plan to allow the Minecraft application window to remain active and be front of other windows throughout Steps 10 and 11. Before proceeding, make sure that you have completed any other activities on your computer that require your interaction or otherwise consume significant bandwidth.When you do so, a new window appears listing all of the worlds on your device. Click 'Confirm' when the 'Replace World?' dialog appears. On the new realm, click the pencil button, make sure the Game section is selected, and select the Replace World button.(I did this by using an hard-wired Ethernet connection and avoiding game & video streaming on the network.) Make sure you have an internet connection that will not be interrupted during the rest of the process.(Specifically, the screen should never turn off while plugged in and the PC should never sleep when plugged in. Make note of the existing settings so you can more easily revert back to them when your are done with this process. In Windows Settings, temporarily adjust the Power settings so the remaining steps are not interrupted by automatic power-saving measures.Make sure your Windows device is plugged in.It may be called something like "My Realm 06/14/20 08:30:00 - Copy." You will need to reference this name in a subsequent step. Make careful note of the full name of the world that you downloaded from the backup.If it doesn't work, Save & Quit, go back to Step 1, and try the next available backup. If it does work, Save & Quit and continue to the next step. After downloading the backup, open this world to make sure you can play it locally, i.e., confirm that it opens and works on your Windows device while it's not on the realm.This will start a download process that will save the world to your Windows device. On your broken realm, click the pencil button, navigate the Backups section, and click the square download button next to the the most recent, working backup. In Minecraft, click Play on the main screen to display the list of worlds.Since my broken realm has been down for so long, I expect to cancel it and request a refund from Mojang/Microsoft.) (I advise against canceling the broken one or making any other changes to it until you know the new one is working as desired. Purchase a new realm subscription, since newly-created realms seem to working.I welcome any corrections, questions, and other comments. FYI, this post applies to Minecraft 1.14.60. Hopefully, people can successfully adapt it to other Bedrock platforms and the Java edition. I'm sharing my process here in the hopes that it might help others. Yesterday, I fixed the problem using Minecraft for Windows 10 and a lot of persistence. One of my Minecraft Bedrock Realms Plus servers has been inaccessible for days, as reported by many other people and several bug reports.