Yeah, it appears that if you edit the FIELD TEXT inside the text editor, it works fine. But when you copy/paste at the RECORD level, it does this.
But it only does it if an actual record for that implied NN does NOT YET EXIST.
If I have PL32 documented w/NN, and PL32:0, PL32:1 have IMPLICIT Nicknames based on PL32. If I manually edit the Extra Info and/or Description for PL32:1, then that record now exists, but it MAINTAINS the IMPLICIT NN for PL32:1 based on PL32 NN (but it has its OWN Extra Infor and/or Description). NOW, if I PASTE an Extra Info and/or Description field from another record to the PL32:1 row, IT WORKS (because that record already exists because I previously created a record for it).
So it is ONLY an issue when the NN is IMPLIED from a "parent" element (e.g. base element of a cast) AND there is NOT YET a record for it (i.e. not yet a record for the cast record). Doesn't seem to bad.