Question about Flightplans

I don’t know if the correct section. If not, please be free to move it.

So, I have a question since MSFS2020 was launched.

The window says that I can load a flight plan (* .pln) at any time:

pic003

This works from the flight creation screen:

But when the flight was already created (inside), it doesn’t allow to load a flight plan file (* .pln)

This is a bug (perhaps unintentional) ?
Could it be fixed?
Or will it just be pushed aside?

Thanks