Intune has been working with the Windows team to troubleshoot reports that custom OMA-URI policies with payloads over 350k bytes are not consistently applied in Windows 10 devices. Based on the results of our investigation, we’re going to block Intune creation of any custom OMA-URI policies that are larger than 350k bytes. We do also plan to put an “unsupported” profile type in an upcoming release to help highlight any existing policies greater than 350k.
If you have policies with payloads over 350k bytes, you should see a message center post and actions for you to take to reduce the policy size. To determine the size of the custom OMA-URI policy, check the file properties of the original xml file used to configure the policy. You can remove or reconfigure the unsupported and assigned custom profile names. Remove the non-assigned customURI profiles. Note that when you unassign or remove custom OMA-URI, enrolled devices will continue to stay enrolled, just the policy may not be consistently applied until you resize and assign the policy.
If you have any questions, just let us know @IntuneSuppTeam or through comments on this post.