Found a bug:
When looking through an active Industrial Turbine (Mekanism), fluids and some tile entities don't render (note: it's not specfic types of TE, half my electric pumps render and half not)
EDIT: the inside of a tesseract and gas tanks don't render either, so not limited to Mekanism TE's
Also, I thought of a mod to add: Immersive Engineering