I have the same issue. I noticed it wipes the k values after restart of the printer. Just calibrated a second AMS and then had a failed print that required the nozzle to be swapped. Anyway, after I powered the printer back on - all k values were unassigned.
They are not deleted - just unassigned from the spools.
Even with the option to update on startup unchecked?
I only have some work when inserting new filament spools, different from previous, which I need to update manually. Otherwise it keeps the last filament and k value for the spool location.
I have now an workaround. I changed the language vom German to English. Now I Can see the different K Values in auto calibration and manual calibration. So I think there is still an bug with the German language…
Nice to know, as there are others with some issues.
Due to work protocol, I tend to have everything in English, substantiating your findings.
It can also be a bug for any language besides English.
I’m confused … isn’t that precisely what I suggested way back in the 3rd reply? And you said it didn’t work?
I tried only „.“ and „,“. Didn’t come to change the language 
Same … At least you can select them from the printer as well.
They’re stored. You have to know where to look. Go to where it shows your spools. Click the pencil. That’s the edit button. It’ll say your k factor.
You seem to be having trouble saving the calibration in the software. This can be caused by various factors, including software errors or incorrect settings.
This post was created over 7 months ago! This failure was an official bug and has long been fixed.