Elasticsearch is new in 7.1.7 and was a bit unstable (although the performance and power gains from the old Lucene search engine are, IMO, worth it even in 7.1.7). Issues were fixed in later versions, and Elastic Search should be largely stable in 7.2+. There's no hotfixes for this I'm aware of - mostly, this is engine-level stuff included in later versions.
The best thing to do is to use the most recent version of Pega if at all possible, for this and other fixes/ features. If you do have to use 7.1.7, you probably won't see the corrupted indexing issue, but if you do the information above should help.