This error causes me problems regularly. Example:
I use the LocalizationResourceManager.Maui NuGet package to make my app multilingual. I therefore add a folder „Translations“ and in this some resx resource files. When I want to set up the LocalizationResourceManager in the MauiProgram.cs file, it tells me, that it can not find the Translations folder, if I start to type
it wont even recognize the Resources folder.
Look into your csproj file: VS may have created such lines:
<Compile Remove="Resources\Translations\AppTranslations.Designer.cs" />
<Compile Remove="Resources\Translations\AppTranslations.de.Designer.cs" />
Delete the complete ItemGroup, this will solve the problem.