Bit of a head scratcher here, decided to through this out to the community since I have a Prem Support case logged and after 20hrs it has still not been assigned. Hopefully someone here knows the answer (or has come across this).
If edge is used for classic search, the result does not open the file linked to the result. The link to the file is returned as https:\\[tenant]\sites\Site collection\Search center\Filename.pdf#search="SearchTerm". Windows 10 (1809) returns "You'll need a new app to open this word …. look for an app in the Microsoft store" This works in chrome and IE without an issue. Of note: This is only happening to our licensed users. If an unlicensed domain user tries Edge will open file successfully.
If you copy and paste the URL into a new browser window for a licensed user it works (not permissions), but if you then try the Search result (clicking link) in results page still does not work.