I'm not sure exactly where it starts to get off, but at least by chapter 9 of 1 Corinthians, the cross-references in NA28 are off by two or three verses. For example, the star before the verse number in 9.24 hyperlinks to "| 2K 11,29 · R 14,1!" which should be associated with 9.22 (the star before the verse is a weird location for a link to cross-references in NA28; this is typically used when the inner margin indicates a kephalaia division).
I don't have my print NA28 in front of me, but I'm not sure all of the cross-references are even found two or three verses below where they should appear; I'm not sure if all of the stars representing cross-references are found in the text, just in the wrong location.
Also, why do some cross-references in NA28 have stars while others have asterisks? For example, in 1 Cor 9.21 an asterisk appears after Christou, but a star appears after anomous (v24 also has a mixture). I wasn't able to read anything about this in the intro of the Logos edition, and since there are no stars in the print edition (the material in the inner and outer margins are just printed in their appropriate locations), there is nothing about them in the print edition.
Thanks!
John Gentry