Cannot for the life of me figure this out, have used MANY different settings, default materials and objects. Nothing works. Really is frustrating thinking yet again Twinmotion has solved all there previous crashes with new updates but hasn't done anything regarding stability. It's like you are hiring software engineers straight out of high school, this is ridiculous.
Hopefully there will be a fix for this ASAP - good luck development team. Thanks for an amazing bit of software - if you get this path trace problem sorted it will be 'nirvana'.