Skipping interaction Id

We are getting below messages in UCS logs.

07:11:52.265 Dbg 29999 [ArchivSvc] Skipping interaction Id:0005SaCAT27P6U83 ThreadId:0005SaCAT27P6U82 Status:stopped EndDate:2017-02-27 17:27:
59.0
07:11:52.265 Dbg 29999 [ArchivSvc] Skipping interaction Id:0005SaCAT27P8FHT ThreadId:0005SaCAT27P8FHS Status:stopped EndDate:2017-02-27 17:50:
27.0

What could be the reason ?

This is standard UCS message covering the archive task