Combination mode doesn't generate all combinations

[atom]

thats good news. but yes, i am still just guessing. if i am right this should produce invalid lines in your debug output file. i mean this is some kind of race condition. the result file will look always diffrent and with no repeating pattern but there should be lines that are invalid. maybe with 1 or 2 char more than expected or 1 or 2 char less. could you please verify that too?

and as a temp workaround you can use -n 1.