AmiBroker 64-bit of most recent development cycle uses new Microsoft Visual Studio 2017 compiler.
See 6.25 for example where there was issue with array division being fixed (because of that new compiler).
Since your 6.20 32-bit version (with old compiler) runs the code fine if DAN is selected it looks like another VC++ 2017 compiler issue in 64-bit version.
if you remove the quotes being O = H = L = C at the start of DAN price fields then DAN will show non-NAN in 64-bit again. So it seems to be compiler issue when there are such bars.