You need all blocks in your normal inventory (not creative inventory) in creative mode when building a schematic

This is a duplicate issue, but the last issue I could find discussing this was two years ago. Could someone let me know if this was ever added, and if so, how to enable it? thanks

No this was not added yet.
I don't know about any attempt at implementing it besides my own implementation, which I never published because it causes problems with #farm and I didn't want it enough to try fixing them.