Hello brooke page,
Since the realm works fine on your Xbox and your phone but only the PC says "not a member" and won't load the Realms page, the problem is almost certainly on the PC's side rather than on the realm itself. A few PC-specific things worth checking that go beyond what's already been suggested:
- Confirm the PC is running Minecraft for Windows (Bedrock), not Java Edition. They look similar but they're separate products with separate realm services. Open the app and check the title bar / launcher.
- Sign out of all Minecraft sessions from the account side. Go to https://account.microsoft.com/, then Security > Advanced security options, and choose "Sign me out everywhere". Sign back in on the PC only and relaunch Minecraft. This clears stale sign-in tokens that can leave one device stuck "not a member" while others work.
- Run the Gaming Services Repair Tool. Microsoft has a dedicated tool that fixes a broken Gaming Services / Xbox identity stack on PC, which is a common cause of PC-only Realms load failures. You can try that out here https://support.xbox.com/en-US/help/games-apps/troubleshooting/gaming-services-repair-tool
- Update Minecraft for Windows through the Microsoft Store > Library > Get updates, in case the PC is on an older Bedrock build than your Xbox or phone.
If none of those work, ask your friend (the realm owner) to remove your Microsoft account from the realm and re-invite the same account you use on Xbox/phone, then restart Minecraft on the PC.
If none of that gets you back in, the next stop is Minecraft's own support, since realm membership itself is managed on their side rather than Microsoft's: https://help.minecraft.net/.
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