@Thomas, Thanks for posting in Q&A.
From your description, I know that you encountered an issue that shared IOS devices have no storage left immediately after the device has been set up.
To clarify this issue, please check following information.
- Check whether the device storage is enough before setting up.
- Change another device to check whether the issue will get fixed.
If the issue is still existing, we suggest that you open case to get more help.
https://learn.microsoft.com/en-us/mem/get-support
Thanks for your kind understanding.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.