Cannot read barcode produced by ZPL Code 39 - barcode

Question

I am trying to print a barcode (code 39) to a label (2" x .75") on a Zebra ZT610 (600 DPI) printer, but none of our 3 barcode scanners will decode the barcode. We are encoding a 14-character alphanumeric value. I created the label using ZebraDesigner, and passed the ZPL to the printer using Zebra Setup Utilities. I also use Labelary to check the label, and change parameter values.
I have tried every conceivable combination of the ^BY and ^B3 commands I can think of, that would fit on the label, including shortening the data for testing (encode only 8 characters). Here is the latest ZPL with a barcode that should be well within the label's printable area, but scanners will not read it:
^XA~JSN^LT0^MNM^MTT^PON^PMN^LH0,0^JMA^PR2,2~SD15^JUS^LRN^CI0^XZ
^XA^MMT^PW1200^LL0449^LS0^XZ
^XA^BY4,3,143^FT82,192^B3N,N,,N,N
^FD2116A83034137M^FS
^FT39,258^AAN,45,25^FH^FD2116A83034137M^FS
^PQ1,0,1,Y^XZ
Unreadable label image:
We also have an old Zebra R110Xi4 (203 DPI) printer that we also print code 39 barcodes to, on the same labels. The barcodes on these labels are perfectly readable by the scanners. This is the ZPL for it:
^XA~JSN^LT0^MNM^MTT^PON^PMN^LH0,0^JMA^PR8,8~SD30^JUS^LRN^CI0^XZ
^XA^MMT^LL0102^PW379^LS0^XZ
^XA^BY1,3,40^FT50,54^B3N,N,,N,N
^FD2116A83034137M^FS
^FT0,73^ABN,11,7
^FD2116A83034137M^FS
^PQ1,0,1,Y^XZ
Are there any suggestions as to what I might try next?
Thank you!