If a blueprint is captured while a combinator has values then those values will be included when being build via that blueprint. They never go away. I did have an ID set to a value other than -1.

Once built they update normally for me.

Interesting. Mine kept the old items (some 10+ rows of them) for at least 10 minutes. Maybe because I took the blueprint from a test sandbox and applied it on a real map?

I'm on vacation right now. I'll try to figure it out when I'm back at the end of the week.

I also found this problem. Once a combinator using the blueprint, it won't be updated automatically.

I too am running into this problem.