Thank you Laurens, I had only tried octetstring which didnt parse it correctly, but using type octetstringascii lets me parse the octetstring into the write formatting. I believe the original response came in as:
Type=”OctetString” ReturnValue=”M3d A1 &#x 0;&#x 0;&#x 0; ” (without the spacing, so essentially null characters)

By me converting using octetstring, I converted this into the hexadecimal value which led to my confusion.
If I use octetstringascii, it correctly parses the problematic character which led to octetstring converting my returnvalue to hexadecimal format.