Hey for the next update for the Blueprints have a enabled button to show what blueprint is ready too be merge that way we don't have to keep scrolling down after we merge one blueprint.
Thanks for the suggestion. The current stage (e.g. III) in the overview becomes green when there is a blueprint of the same type and stage available. Sadly this doesn't take the product's dependencies into account. I will see, if I can fix that in one of the next updates and make it easier to recognize. I hope this helps already, but I consider to add the filter you suggested as well.
Did you move cities? If your investments in building go down, content will re-lock until the investment is met.