I would have thought that “Rendered” would display glass as I can achieve a close glass rendering with the “Custom” setting.
In addition, Glass looks like glass when rendered as “Raytraced” but the “Custom” and “Plastic” samples have no transparency as they did when rendered via “rendered” setting.
Hello - yeah - Rendered display mode will never look right for glass-like materials - at least not like ray tracing - that is why ray tracing is needed and takes extra time. However it does seem like Rendered could maybe fake the color part at least a little.