Internal disc speed on M1 Max studio numbers are off. Did I do it wrong?

[n8mac]

I tested my external Samsung 4TB 990 nvme and got this...

I guess that's about right as it's in a cheaper enclosure. When I went to test the internal I was told I didn't have permission to write, so I created a 8gb disc image on the internal and tested that. Results look just a bit off...

 

[Bigwaff]

When I went to test the internal I was told I didn't have permission to write, so I created a 8gb disc image on the internal and tested that.

Did you give BM app Full Disk Access in Settings > Privacy & Security ?