If the tree still have leaf on, I think it is possible to draw the conclusion that it has not been cold enough for it to shed leafs.

Sorry, I don't know If that is an issue for the species. Some decidious species can go without shedding a winter without shedding without any apparent health issues. Most species cannot.

I appreciate the insight, no worries on the uncertainty of the species. Perhaps I'll give this some more time and see if any change in weather might bring results.

Another thought. maybe the cold frame is sheltering the plant too much for the needed seasonal reaction? Its out on my balcony and has an open bottom. Thing is, someone lives directly below my condo and there may be a certain amount of heat captured through the floor. Might just try and gauge the temperature and see if there may be something to that. My other deciduous have all dropped leaves, but I could probably do more to understand the specific temperature needs of a smoke tree/bush.

Typically one lets trees go fully dormant before putting them "to bed" in a cold frame. Why did you move it into shelter before the leaves dropped? Did you get such a cold spike?

Normally, deciduous temperate species need to get a bit of frost to get into deeper dormancy.

I was encouraged by some experienced members of my local bonsai club to put them into shelter as we were getting a pretty abrupt cold front back in early November. It was even suggested that my deciduous trees go in there (and stay there) before leaf drop.

For reference, my other deciduous trees dropped their leaves and seem to be doing okay. I say so because their branches haven't gone brittle. (note: beginners intuition)

My trees don't receive much light in the frame, but remaining leaves aren't exactly dried or brittle either, so it would seem that the tree is still alive? (and I'm thinking dormant?)

I've also read into a condition called Marcescence. I'm not sure exactly how to identify it, but some reading into it would indicate that trees can go dormant without dropping foliage. Something about how abscission cells require a degree of cold weather to react, however in circumstances when they don't, the tree will keep foliage until spring.

Does all of this sound out of the ordinary for overwintering or is this something that has been experienced?