I upgraded from a Watch 6 to Ultra 2. As well, from iPhone 12 Pro Max to 15 Pro Max. And switched from ATT to Verizon. So, thought this had something to do with my "it's complicated" situation.
I'm seeing the same thing. More often than not I get dashes. Sometimes though I get values. Sometimes I will see values if I switch to another face. Sometimes when I switch back to the first face, I get values. Sometimes not.
If I tap on the complication, I do get weather data. And sometimes when I go back to the face then I get values. And then I'll glance at the watch later, and no values.
Given the number of responses, here, I suggest:
"It's broken".
10.0.2 on Watch Ultra 2.
Think I'll be spending more time here again. Google search is another thing broken - that is, across the board, not related to iOS. They've been punked by low-quality content-mills, and so if you search for any solutions for iOS problems, you just get badly-written, barely-comprehensible inaccurate junk. And I don't think Google is able to solve it.
But glad it nudged me to come back to where I can get some answers!