ShareSync Not Syncing New Items After New Config/Hardware

I am hoping someone can help me here.
My previous data sync setup was I had a PC syncing with a DS1621 via Synology Drive, and the DS1621 syncing to a DS220 via ShareSync. To my knowledge, this worked between all points with no issue.
I have changed that up to where the new source is a DS923 which I am trying to replicate the data files to the DS220 (will repurpose DS1621 + add 517 for backup/other work). The DS923 is creating folders/files via various Containers, and it seems the data additions - and even file name changes - created by those Containers (user: docker) will not sync to the DS220. After various troubleshooting/guessing, I wiped the DS220 and started it over, only to find that issue remained. This seems like a permissions issue but I am not seeing anything glaringly obvious.
I am unsure what other information to provide, but can provide anything needed for any offered assistance.