imaplib copy Email to Folder (subfolder) on live.com

Question

I am trying to copy mails from Inbox to a subfolder on live.com. Due limitations of the system, I only can work with the default libraries of python 3.8. The code to list the directories of the account looks like this:

imapcon = imaplib.IMAP4_SSL(imap_host)
imapcon.login(imap_user, imap_pass)
for i in imapcon.list()[1]:
    print(i)

The result is:

b'(\\HasNoChildren) "/" Archive'
b'(\\HasNoChildren \\Trash) "/" Deleted'
b'(\\HasNoChildren \\Drafts) "/" Drafts'
b'(\\Marked \\HasChildren) "/" Inbox'
b'(\\HasNoChildren) "/" Inbox/check'
b'(\\Marked \\HasNoChildren) "/" Inbox/stuf'
b'(\\HasNoChildren) "/" Inbox/test1in'
b'(\\HasNoChildren) "/" Inbox/test1st'
b'(\\HasNoChildren \\Junk) "/" Junk'
b'(\\HasNoChildren) "/" Notes'
b'(\\HasNoChildren) "/" Outbox'
b'(\\HasNoChildren) "/" rootstuff'
b'(\\HasNoChildren \\Sent) "/" Sent'

My code to copy looks like this:

resp, items = imapcon.uid("search",None, 'All')
items = items[0].split()
for emailid in items:
    cpres = imapcon.uid('COPY',emailid, 'Inbox/test1in')
    print(cpres)

Unfortunately, the mail will not be copied. I found mostly Gmail folder specific hints, but nothing worked out. Tried cpres = imapcon.uid('COPY',emailid, '/test1in') or cpres = imapcon.uid('COPY',emailid, '\Inbox.test1in') I found examples with brackets.... so I tried cpres = imapcon.uid('COPY',emailid, '(\Inbox/test1in)')

To make life easier, I tried to copy the folder rootstuff cpres = imapcon.uid('COPY',emailid, 'rootstuff') and this works fine. To the Inbox/Subfolders not. Where is my mistake?

EDIT:

the print for cpres = imapcon.uid('COPY',emailid, 'Inbox/test1in') is

('NO', [b'[TRYCREATE] The destination mailbox could not be found.'])

and for cpres = imapcon.uid('COPY',emailid, 'rootstuff') the script prints

('OK', [None])

I am not sure but I doubt it is something with subfolders.