Tried to Move a Folder with Subfolders & Messages but it did not work fully

Question

As far as I know, Drag n Drop should work - but not into or out of any IMAP account. Only between Local folders and folders in POP accounts.
I moved a subfolder (Clients) under Inbox in a POP account to Local Folders. All the subfolders (a folder for each client) moved, or I should say, copied, as all the folders remained under the original POP account. Also, only four of about 60-70 folders' messages copied as well.
How do I fix this? Is there some way to safely ensure a successful movement? I don't want them in both places.
Help!!
Note that the reason I am moving is simply reorganizing. As well, my providers are now offering IMAP so the only way I know how to "convert" an account from POP to IMAP is to turn off the POP and create a new account. I've done this successfully with two email addresses, but I want to also move the old email subfolders as well.

Answer 1

So, just to refresh... I believe I did select, then dragged & dropped. Just the folders were created; and of the 60-70 folders only the messages of 4 subfolders were copied, not moved.
I just reviewed How to Switch from POP to IMAP:
'''Transfer your local messages to the server'''
If you have messages or folders in your POP account that you would like access via your IMAP account, simply '''select them and move them to your IMAP account by dragging and dropping'''. Depending on the number of messages that you move, it may take several minutes to be uploaded. Be patient; you are nearly finished.
From: https://support.mozilla.org/en-US/kb/switch-pop-imap-account#w_transfer-your-local-messages-to-the-server