I found an anomaly in the creation of the Gedcom file via Generate Report:
After the sequence of individuals and before the sequence of families, a block of 9 lines of empty events is created, for each individual linked by internal link with another individual.
This is the block that is repeated for n times:
1 DEAT Y
1 CHR
3 DATE
1 RETURNS
3 DATE
1 EDUC
3 DATE
1 CENS
3 DATE
The number of these (useless) blocks in the .ged file corresponds to the number of internal links in the .gno file.
I enclose a small .ged file and a .gno file, for a better understanding of the problem.