Plugin Header Menu stops indicating the upsample status (on or off) when a custom sample rate (other than 2x the project sample rate) is entered in the AUD.IN file.
 
For example:Project@96kHz
file : AUD.IN
[PluginUpsampler]
//Molot
{141AC902-4D4C-5432-4D4F-4C4F54307E31}.EnableFlags=1
{141AC902-4D4C-5432-4D4F-4C4F54307E31}.SampleRate=384000


In this case the Molot Vst Header menu stops indicating the upsample status.

Does Molot support 384K?
 
I just tested with FabFilter Timeless 2 with a project at 44.1K and an upsample setting at 96K. It seems to work OK.

This info from the eZine might be helpful: The maximum upsample rate is 384 kHz, so upsampling is not available for projects that run above 192 kHz; and at present upsampling cannot be applied to plug-ins in surround buses, or to bit-bridged plug-ins or region effects. Finally, note that some plug-ins may not support operating at a higher sample rate. In this case, SONAR displays an error message toast notification, and performs the plug-in bounce at the original project sample rate.