Error on split file generated filenames

[cwolter]

Using 10.0.2 Standard.
I'm splitting a file in chunks based on a repeating string.
I want the output files names like: original_1.txt, original_2.txt and so on.
If I set the split filename pattern as: %f_%4.4d.txt I obtain original_0001.txt....
If I set the split filename pattern as: %f_%d.txt (as per the help specs) I obtain (!) a number of original_.txt files....
No incremental number is ever added.

I don't want 0's in front, but the chunks are more than 1 thousand, so....

Is it a bug ?

TIA

[DataMystic Support]

It might be - what happens if you use %0d instead of %d?