@SeanMc5 Can you be more specific in the ask? what kind of images you have in folder A, What's the size of each asset and overall folder? Are they getting synced successfully if you are manually re-processing the asset again using DM::Reprocess asset workflow?
Based on that we can guide you better on the solutions?
Ideally if you can take the Migration example/use case -- It is recommended to turnoff the DM/DAM Metadata writeback kind of workflows, perform asset migration, and then run above workflows small subset by subset ...as they 1. they cause heavy load on the system if run in bulk, 2. they may cause timeout and other Sync issues and fail.
So if folder A is heavy in enough, then it might fall in above scenario.