arcpy export pdf not all labels displaying

I have a python script that updates an xy layer event in a mxd updating point locations.
It also updates labels for this new xy layer event.
It then exports the mxd to pdf.

I have noticed that only my labels that are integers within a text field are shown in the .pdf.

I am using the labelClasses property of the layer and setting the expression equal to
"<FNT name = 'Arial' size = '12'><BOL> & [LABEL] & </BOL</FNT>"
showLabels = True
showClassLabels = True

where [LABEL] is a valid field name and only displays if the field "LABEL" contains an integer which is a string value of an integer.

The field "LABEL" is a text field.

If I pause my script and look at the mxd, before exporting to .pdf all labels show up properly. Only after I export to .pdf do the string labels not show up in the .pdf.

I am not able to post the script sorry.

"1", "1234" work fine
"foo", "1,234" do not display in my pdf.

Any ideas on what could be wrong?