Strange Behaviour creating new Drive Pool

Hi

Today I tried to build my Drivepool new from Scratch.

I attached 2 pcs. 8TB (expand in future every time by 2 pcs) and 2 pcs 1TB SSD for cache.

In the Image1 you can see the 8T Drives as "ARCHIV A 1" "ARCHIVE B 1" and the 2 Cache on the left side in the Diskmanager, on the right side, stable pool is not created.

I add "ARCHIVE A 1" to Pool as the first drive.

If you look at the Diskmanager in the Image 2 on the left side only a 2 TB Drife is created. If I attach all the other Drives, and try to copy a lot of files to the Pool Drive, the pool breaks if the limit of 2TB is reached.

Can you help me please.

Thanks a lot

Best Regards from Austria