See this post, maybe it helps:
You can modify the result source or only the search result query in e.g. a webpart by adding to the query -property:"value" (see, that there is a '-' prefixed before the property name to exclude results with ...
Installing SharePoint 2019 (KB5001944) July 2021 update fixed the issue.
Auto managed property disappear from search schema but is searchable and works as expected.
No full crawl or service application recreation required.
According to my research and testing, this is the correct search results
(*) as a wildcard, it means that as long as the file named with "btwaste" begins, it will be searched. Therefore, the BTWaste.RN_specsheet.pdf and BTWasteCI.RN_specsheet.pdf can be searched.
"BTWaste.RN_specsheet.pdf" is composed of "BTWaste", "...
Recently we had some issues where result were displaying some times and other time it would only display result from On prem. What we found was increase the search query time out displayed the result fine. OOB the default timeout is 1200 ms. We increased it to 1700 ms and all was fine after that. This post helped us to increase the time out. https://ekhichdi....
You can use IsDocument managed property to filter out the list items. The search Get API should look like this
apart from IsDocument managed property you can also use
contentclass:STS_ListItem_DocumentLibrary - if you want to search within document libraries only
In the code provided by you, the apiEndPoint contains the path to the all document view URL. If you hit the same URL in the browser then it will not return any results as path before the "/_api" should be the web/site relative URL.
You can change the apiEndPoint like below and then check
var apiEndPoint = "https://server/sites/mysite/_api/...
Normally, the name is displayed by default in the library, and the title is not displayed. If you want to display the title, then you can go to the setting in the view to display the title column.
Go to libarary settings>Views>All items, and check the Title column:
Then you can display the title column when you search again: