Building Asp.Net project with Core 3.1 and .Framework 4.7.2

I am trying to build a project I started in Windows. It is an Asp.Net MVC project. It has .net core/standard and Framework 4.72 projects in it.

I am on opensuse tumbleweed, and have installed the mono-complete and mono-xsp packages, as well as the .Net Development pattern.

When I try to build, I keep gett the following error: 

Microsoft.Common.CurrentVersion.targets(1216, 5): [MSB3644] The reference assemblies for .NETFramework,Version=v4.7.2 were not found. To resolve this, install the Developer Pack (SDK/Targeting Pack) for this framework version or retarget your application. You can download .NET Framework Developer Packs at https://aka.ms/msbuild/developerpacks.

My /usr/lib/mono loosk liek this:

  linux@142-165-103-193:/usr/lib/mono> ls

2.0-api    4.5.2-api  4.7.2-api   gtk-sharp-2.0              xbuild

3.5-api    4.5-api    4.7-api     ikvm                       xbuild-frameworks

4.0        4.6.1-api  4.8-api     mono-configuration-crypto  xsp4

4.0-api    4.6.2-api  boo         monodoc

4.5        4.6-api    dbus-sharp  msbuild

4.5.1-api  4.7.1-api  gac         nunit