Mac: Import from external SD card thumbnails not showing first time

While working on the mac version of Lightroom (5.1) I have some issues when importing images. When I select the external drive it shows the number of pictures in gray blocks (not selectable). When I cancel and select from a Finder location, then selecting the same external drive they show correctly up. And when I try to import again directly from the external drive they do show up correctly.

I tried already to give Lightroom full disk access but this didn't change anything.

The steps to reproduce:

1. Select the external drive (Untitled):

2. Lightroom shows the following (I can hoover over the light gray tiles and it shows the file name but that's all I can see or do):

3. Then when I close and try again via Bladeren (English: Browse) and select the same external drive:

4. Then I select the folder on the external drive

5. And now it shows all the pictures and I can select them:

Some extra info:

- I did install Lightroom from the Mac AppStore (5.1)

- Files I use come from my Fujifilm X-T4 (Lossless compressed)

- My macOS version is 12.1 (M1 MacBook Pro)