Hello Wesley,
I would suggest you to raise a CSN ticket to SAP to get a standard fix.
I think that a workaround would do till you get a standard fix.
Class: /SAPSRM/CL_CH_SOA_DO_PO_ITEM
Methos: MAP_LONGTEXT
You can create an internal enhancement for the time being and remove/replace the symbols which are creating issues.
I am not sure but BAdi BBP_LONGTEXT_BADI may also help.
Can you please mention the details about SRM version and SP?
Regards,
Arun
Singh