I just downloaded Android 26 (8.0) and 27 (8.1) SDKs with the SDK manager to align my system with another dev working on the same project and found the SDKs don't show up in the Android project properties target platform.
I checked to make sure there were no updates in Visual Studio Tools/Extensions and Updates manager and there were none. So was still puzzled.
I thought maybe VS wasn't showing what was in the platforms folder:
C:\Program Files (x86)\Android\android-sdk\platforms
So I went and renamed some of my older SDKs and sure enough, the renamed folders disappeared, so it was reading the SDK versions OK.
So maybe there was a VS update I wasn't getting? After a bit of googling I found that you can manually check for an update via the VS installer:
- Locate the installer under Apps & Features
- Click Modify
- If there is an update available the Update button will be available
Once updated the new SDKs appeared :-)