I have seen an autosummary of OSP routes on a L3 Switch. For example, if you have a 10.1.1.0/30 and 10.1.1.4/30, learned on a MX by AutoVPN and advertised by OSPF to a L3 MS, it is summarized to 10.1.1.0/29. But when you have 10.1.1.0/30, 10.1.1.4/30 and 10.1.1.12/30, there was a summary 10.1.1.0/29 and a single specific route 10.1.1.12/30. There is no summary to /28. I supposed it to be a feature, not a bug. I did not find any information about it in the documentation.