Can't save project

After I am finished working on a project, I press “File->Save” and nothing happens. The same thing happens when I click “Save as”, “Save all”. Also, when I exit the program, I am notified with a dialog box that says I have not saved my project and when I click save in the box, again nothing happens and I lose my project.
I also tried to export a flow, but after I click export, it pops two new dialog boxes saying “An error occured” and “Error saving file”.
Changing default file path for saving project also didn’t work.
How can I save my projects?

Where are you trying to save the project? Is it in a read-only folder or something along those lines?

Have you got to the end of the 30 day trial period, perhaps?

Are there spaces or “illegal” characters in your file name?