Rejoined the insider preview....

Join the Xbox One Update Preview

Because of overwhelming response and limited space, we’re not currently offering a way to invite friends to the Xbox One Update Preview. We’ll let Insiders know if this changes in the future.

Note If you previously participated in the Xbox Preview Program, you can rejoin the Xbox One Update Preview at any time by selecting it from the
Insider content list in the Xbox Insider Hub.

For more info about the Xbox Insider Hub, see the
Xbox Insider Hub support page.

For more info about providing feedback, see the
Report a problem support page.

Sorry to hear it. If you're in the Xbox Insiders Preview program please use a PC to download the Insiders App and leave the program then factory reset your console again. This should solve the problem.

You'll be able to rejoin at your current level after that's done.

As for your home internet try unplugging your modem/router for at least 60 seconds to clear any issues there.

Hi try removing the console from the insider programme then rebooting the console you can rejoin the insider programme if it works or not.

Hi Volcannon,

Yes, you can rejoin after leaving at any point. It's possible that by joining and gaining exp so that you move up the preview rings to Delta at least so that you may get a future preview update where this issue is addressed and you can test it out for yourself
before those in the Omega ring or not in the preview program. Beta ring previews updates before Delta ring and the Alpha ring, where updates are tested first, requires an invitation to join.

Either way a solution to this will more than likely be tested in the preview program first. News regarding what is included in recent preview updates for the different ring levels can be found here:
https://news.xbox.com/en-us/insider/

Also here is an FAQ all about the Xbox Insider Program:
https://support.xbox.com/en-US/xbox-one/console/xbox-insider-program

Yep,spot on.

At the moment any digital content bought while in the preview program is only playable on a console in the preview program

You'll have to wait until the next update is released to the public before you can play your game or try & rejoin.

The next update should be released to everyone sometime in August but that's not conformed.

You can try & rejoin the preview but it's not guaranteed you'd get back in.