There's a know issue about compiling the R23 sdk with Visual Studio 16.9.
Trying to compile with this version will lead you to the following error:
Error C2079 'maxon::ResultBase<RESULT_TYPE>::_value' uses undefined class 'maxon::BlendAnimationRef' math.framework <path to the file> 571
This issue will be fixed in the next update.
To fix the issue, open the file objectbase.h of core.framework and change those lines :
around line 1088:
// template <typename I, typename = I*> struct VirtualCreate
template <typename I, typename = I*(*)()> struct VirtualCreate
around line 1102:
// template <typename I> struct VirtualCreate<I, decltype(I::Create())>
template <typename I> struct VirtualCreate<I, decltype(&I::Create)>