If rebuilding doesn't work can you close out of VS. Delete the bin/obj directories. Re-open the project and then try and compile again?
Please make sure you're on the latest version of VS
Please make sure all your Android SDKS are up to date (Tools => Android => Android SDK Manager).
When you release your application, did you unselect the aapt2 ?
Could you share a demo with us? If you have tried migrating AndroidX tool and above steps.