MyCloud 4Tb Device

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1

This is probably off-topic, but there is no category that matches my device/problem.
I have a MyCloud 4Tb device that I use occasionally to backup my, my wifes and four childrens’ PCs and Laptops. It is about a quarter full. I say this because I cannot reformat the device as I don’t have enough space to back it all up. Cloud storage I would probably have to buy, but I’d rather do it a different way if there is one. I have a relatively slow network, and it would take a long time to copy that many files.
I have today created a folder, for some photographs I have recently digitised - and within this folder I have created 125 more to separate the years into manageable quantities.
I got carried away with the folder creation cause it was quicker that way and did not check them till I had finished.
So, when I listed them, I could see 60 of the new folders, but not the other 65. I know they exist, because if I create one in a higher folder that I know should be there then try to move it to the correct place, I’m told it already exists.
So how do I access the last 65 without rebuilding anything?