_Rst logs not getting created

Hi Stefan,
we faced an issue regarding "_Rst" logs generation.
After i was trying to publish old archive trends,I found that few of the tags are not having _Rst logs. Hierarchical logs were already configured, group rescanned, archive was auto scheduled, tried with manually archive also but _Rst logs was not getting generated.Trends of tags which dont have any _Rst logs plotted more than the max log configuration time.(Seems strange to me)

so I created those logs(_Rst) manually by Archive Maintenance tools. Now it seems to be working fine.
My concern is why generation _Rst logs of new tags was not happening even after scheduled archiving?
How should i Proceed to narrow down the cause ?
Just want to avoid repetition of issue.

System Used is 5.1revD RU3 with both AC800M and AC460 controllers in backend.
Thanks in advance.