Leica summicron aperture display

Dear Community !

I have recently acquired a Leica 50 mm Summicron. Today I only took photos with this Lens on a Leica M with aperture 2.

After importing (Lightroom Classic 10.0, Raw 13.0, Mac Catalina 10.15.7) I noticed that in any view always aperture values between 2.4 and 4.0 are displayed. I carried out a related test afterwards, but aperture 2 was not correct displayed. The Summicron itself as lens for a photo is displayed correctly.

Any Suggestions ?

best regards

Rudolf