black screen issue (no video thumbnails) in import tab

I have PP Beta 22.1.0.110 on windows 10, and a black screen issue (no video thumbnails) on import tab.

Steps to reproduce : 

0) In PP Beta preference/General, I had selected: "at the start, open the most up to date" (in my example, the most up to date was to open on "Modify tab/project".

1) When I open PP Beta I am on "Modify tab / Project".

2) I click on "Import tab" and select 3 thumbnails.

3) I close PP Beta

4) At the reopen PP Beta, I am on "modify tab/media explorer".

5) I click on "import tab" and you can see that import tab is black (no video thumbnails). So, PP Beta does not load the "import tab" content.

Even if I trash preference, I have all the time this problem.