Hello,
I recognized the same issue with the latest Matomo v3. www.startpage.com and eu.startpage.com are classified as websites and not as a search engine. This happens even General['enable_internet_features'] is not disabled here.
So I tried the console command mentioned in the Github issue:
console core:run-scheduled-tasks --force "Piwik\Plugins\Referrers\Tasks.updateSearchEngines"
The task is successfully executed but this does not solve the problem. As an alternative an SQL query was mentioned to delete the SearchEngineDefinitions field.
But I’d like to ask first if this could be really the solution. I don’t want to mess up the Matomo installation completely with executing raw queries on the database. It would feel more comfortable solving this with the console command so I wonder why this does not seem to have any effect?