ZPL - Barcode Missing a digit when printed

The >; inside of your ^FD block is telling the code 128 barcode to go into a subset (subset C in this case) which forces the data in the barcode to be numeric pairs (00 - 99). Any data that is not supplied in numeric pairs is ignored. If you put a letter in there, it will ignore that pair. In your case 9102100 has an odd number of numbers, so it ignores the last one. If for example, you add another 0, it will put all the letters in the barcode.

The ;> which puts the barcode in Subset C is not the default. Subset B or :> is the default which will allow any character to be encoded in the barcode. So you can replace the ;> with :>, or just remove the ;> entirely, and it will print out properly.

Check out the ^BC documentation in the ZPL programming manual for more information about Code 128 subsets and data validation