@bkarki1 I had the same issue on a LCA we were performing, the conversation PoCP impact in CLT Structure Buildings - #3 by xramon I started is in the same page of what you posted.
My conslusions so far were:
Conclusion 1: POCP seems to be higher in a CLT structure if compared with a Reinforced Concrete structure.
Conclusion 2: POCP in CLT is produced in A1-A3, specifically in A1: extraction and process.
Conclusion 3 (to be confirmed): Terpene seems to be the responsible of higher POCP in CLT during A1 phase ¿?