The dbAdmin role has the permission to drop the system.profile collection, but does not have permissions to create it (e.g. for resizing).
Admin users may drop the system.profile collection in an attempt to resize it but are then unable to re-create the new collection manually.
Create a new user-defined role that grants the necessary permissions and add that role to a user, as described in this comment.
All production releases from 2.6.0 to 2.6.3 are affected by the bug.
The fix is included in the 2.6.4 production release.
Added the permission to create system.profile collections to the dbAdmin role.