FTP 550: access denied

For a few days I have the next number:
– When I try to delete some files with filezilla or winscp ftp from my blue ftp website, I got 550 accesses denied

if I am using the kudu console, I can delete the files, but when I use the ftp client (fileziila or winscp) I still have these files on the blue server, I even deleted them before the kudu console!

Anyone saw a similar problem?
I never had this problem in years

Thank you