Save project did not work

Hi,

Yesterday something very frustrating happened with Premiere Elements 2020.
I started a new project and had been working on it for more than 4 hours.

I clicked Save at least once every 15 minutes.
There were no errors during the save.
When I wanted to export the project to an MP4 file the progress bar didn't show anything.

Therefor I stopped PE and restarted it.

I reopened my project and discovered that it had the status from several hours ago.
90% of the work was lost! That didn't improve my mood, to put it mildly.

I don't know what happened. I've never seen that before.

In the auto save folder there was nothing, no files at all for this project.

I saved the project as a different name and in a different folder and had to redo the 90%.

I also reopened the file with the problem and it still does not save any change.

Any ideas how to prevent this in future projects, except for checking the date of  the project file after each save?

kind regards,
Reyer
The Netherlands.