Why can't Visual Studio locate steam_api.h?

Software versions used: Visual Studio 2017 (issue also occurs in VS 2019), UE 4.26 (source engine downloaded from Git’s “Release” version). Windows SDK 10. Windows 10 x64

I’ve followed UE4’s Steamworks SDK setup and my Steam functionality works as intended so far when I run my uproject in standalone mode. However, I’m trying to make a packaged version - but I’m getting a fatal error that says VS can’t open or locate steam/steam_api.h. I’ve made sure the file is in the appropriate folder and added the directory to the project’s include directories. I’ve tried changing the way it’s called in the files - changing “” to “/”,"<" to “”, and so on. The error still remains. What could be causing this error?

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