Is there a size/amount limit to AOMEI File Syncing ???

I have successfully been using AOMEI Standard BackUpper to create system images on several machines.

Yesterday, I decided to give folder synchronizing a whirl.

I set it to work synchronizing one of my pictures folders from one external drive to another; plenty of empty space on both.

Involved were 18,768 image files in some 300-plus sub-folders; some 400-GB worth.

At first, I thought this is going to be the trick; it was pouring files into folders like corn through a sheller; then, after accomplishing four sub-folders, it just stopped and said mission successful.

It knew there was MUCH more to be done, as it proclaimed the 18,768 files there when it started.

I renamed the top folder it created and ran it again twice, each time with the exact same results; I restarted the machine and tried again; I restarted the machine, created a new task and tried again --- exact same results.

For what it is worth, this ain't some Walmart special machine that might be bogging it down.

Is there a size limit as to what it can do ?

Did I just give it more than it could cope with ?

As an experiment, I created a new root folder in the source drive and have been dragging one next-level batch of sub-folders into it at a time, pressing "sync now" with each addition; so far, it is recognizing each new batch and adding them to the destination.
I still have a long way to go; I hope it doesn't get partially through and choke again.

On EDIT: What is it doing when it says "creating snapshots" ?

Thanks for reading.

You could try asking at the forum
EDIT- I notice you already have. I don't use that feature, perhaps someone else here does.