@Justin Lee Thanks for posting in our Q&A.
For this issue, if the target device is assigned the device category "Information Technology", we appreciate your help to collect some information:
1.Please check the dynamic rule processing status.
2.If everything looks good, please allow some time for the group to populate. Depending on the size of your Azure AD organization, the group may take up to 24 hours for populating for the first time or after a rule change. When the processing status shows "Update complete", we can check if all the devices have been added to the group.
If there is anything update, feel free to let us know.
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