IPL (Intermec Printer Language) never specified the length of a label, it relied on the user to format the data properly; if you went over the edge, it would happily print on the next label.
The new PM series printers behave differently. When you define a label size image memory is allocated based on those settings. Anything that falls outside those limits will get chopped off. IPL is now a Fingerprint program that runs on the PM43 so there is a conflict between the two languages on this label size issue.
Here’s the same data sent to a PX (top) and a PM printer (bottom):

This usually won’t be a problem if your labels are set up correctly and don’t run over the edge of the label. However, there’s an IPL command (<SI> L) that’s misnamed “Maximum Label Length” that sets the label length on the PM and PC series running IPL. To quote from the IPL reference manual “Notes: The printer uses this number for detecting media faults. It does not use this
number to limit the image size of a format on the label.”
I think mapping this configuration command to set the label length is a bug, but I understand how this could happen. They way to get around this is to implement the “Ignore IPL” commands feature in the PM43.
To get the printer to ignore an IPL command you have to turn on this feature; the easiest way is through the web interface. Sign in as “itadmin” using “pass” as the password and click on the Configure tab, then the Languages link on the left, then IPL, and you’ll see the Commands Ignore pull down in the General Settings:

Enable Commands Ignore and press the Save button.
You can enable this from the front panel menu too. Go into Settings, down arrow to Languages, General Settings, then enable Commands Ignore.
Enabling this will cause the printer to ignore these commands:
<SI> d dark adjust
<SI>g media sensitivity
<SI>c cutter enable/disable
<SI>D end of print skip distance
<SI>F top of form set
<SI>f label rest point
<SI>L maximum label length
<SI>R label retract enable
<SI>r retract distance
<SI>t self strip enable/disable
<SI>W set label width
<SI>X label origin, X Y adjust
These commands are contained in a file named IGNCMDS.CFG in the /home/user/config/ipl folder. You can add any SI command you want ignored here, or you can delete the command that you still want the printer to respond to. Copy this file to your PC using and FTP client, edit it, then copy if back to the same folder.
Note: Loftware normally sent out the maximum label length configuration of 5 inches (<SI>L1000) with their compiled files or Print Server product when sending data to IPL printers. If you see your label length being reset to 5 inches, it’s likely that Lofware is the source of this IPL data string.