Attaching the Type Cover to the SP4, with power either on or off, is the kiss of death for my SP4.
Like you, I dock my SP4 in the SP3 docking station (which Microsoft says is fully compatible, if you ignore the fact that it makes a solid and reliable connection only about 80% of the time, even with the official Microsoft SP4/SP3 Dock Shim (P/N TP3-0001
which is free a the Microsoft Stores, if they're not already out...) I will say that as poorly as my SP3 dock works with the SP4, it does seem considerably less demon-plagued than the new Surface Dock, which (based on posts in this forum) appears to be just
as unstable and unfinished as the rest of the Surface Pro4/Book family.
If I NEVER attach the Type Cover at all, then my SP4 will wake from sleep *most* of the time. (Until the timer runs out and it sleeps anyway, at which point it's wedged up hard again. Yes I realize I *could* live with hibernation for everything, but see
my earlier posts on that - that is definitely NOT what Microsoft intended as normal, or what they set as the default, even today, after months of horrendous problems.)
About half the time, I'm just using my SP4 to take notes and do a little light duty e-mail checking when it's not in one of the docks. I can get by without the Type Cover for that, but actually doing any kind of document creation is out of the question
on the touchscreen keyboard.
Reminder, the Type Cover (remember the "click-dance" ads and "Lapability"?) are one of the main things intended to set the Surface family apart from "consume-only" devices like the iPad and Android tablets. Sadly, Microsoft has decided to ignore its promises,
and doesn't care on bit about customers not being able to work and losing data. (I'll believe differently when Microsoft posts something acknowledging this problem. I'm not holding my breath...)