Trigger re-index of part of a document library or files of a certain extension in Sharepoint Online

Question

I have a gargantuan set of document libraries that each contain a folder with msg files. I set a few managed properties specifically for the folders with msg files in order to make a custom filter for these properties in a search center. The search and filters work, but only newly entered msg files are being picked up. The formerly entered msg file properties are not present in the new managed property indexes which were only recently mapped. I want to trigger a crawl of just these subfolders, which all have the same name and are nested inside larger document libraries. Is there a way to do this using PnP? I already tried using Request-PnPReindexList -Identity "list/sublist". There was not an error, but it has been over 24 hours and the list has not been indexed.

I also tried reindexing one of the entire document libraries using the SP front end Library advanced settings > reindex library. It has been about three days and it has not been reindexed yet. My preference would be to set reindex for only the msg file subfolders so as not to overwhelm the system, which has many terabytes of documents divided into dozens of libraries. Thanks in advance for any advice you can provide.

Answer 1

Reindexing can only occur at the Site or List level, there is no further granularity offered.

Because this is SPO, you may want to open a support case. They can likely provide further detail as well as information on the last time the location was indexed.