Figma - won't save as .fig or import layouts?

Question

Figma

The customer sent me a .fig layout, opened it, edited it (made changes), then I want to save the layout for transferring the file to the customer, I click save as .fig - and it saves the layout simply as an unknown file. Then I try to open it in Figma and writes Files failed to import....
I understand that you can give a link, but the customer asks for a file. How can I save the layout so that I can open it later?

Answer 1

A few questions:
1. How do you open a Figma file?
2. Have you tried restarting Figma and exporting again?
3. Can you attach the Figma file here so that I can try to open it for myself?