I have a similar problem.
When I run the three suggested commands, I get:
~: R RHOME
/Library/Frameworks/R.framework/Resources
~: ls -l /Library/Frameworks/R.framework/Versions/*/Resources/lib/libR.dylib
-rwxrwxr-x 1 root admin 4071728 Jun 23 19:50 /Library/Frameworks/R.framework/Versions/4.0/Resources/lib/libR.dylib
-rwxrwxr-x 1 root admin 4071728 Jun 23 19:50 /Library/Frameworks/R.framework/Versions/Current/Resources/lib/libR.dylib
~: 3dMVM -help
updating R_LD_LIBRARY_PATH ...
oo Warning:
Failed to load R_io.so with this error message:
Error in dyn.load(ll) :
unable to load shared object '/Users/knutsonk/abin/R_io.so':
dlopen(/Users/knutsonk/abin/R_io.so, 6): Library not loaded: /sw/Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libR.dylib
Referenced from: /Users/knutsonk/abin/R_io.so
Reason: image not found
Calls: source ... withVisible -> eval -> eval -> set_R_io -> dyn.load
Execution halted
Any help with this? Thanks.