SFTP won't overwrite file

Ubuntu 20.04
Virtualmin 6.16

I have a problem with SFTP.
Uses FileZilla and connects via port 2222
You can log in and see folders and files in /home/DOMAIN/public_html etc.
The sftp.log shows:

mod_sftp/1.0.0: user ‘xxxxx.com’ authenticated via ‘keyboard-interactive’ method.
unsupported ‘simple@putty.projects.tartarus.org’ channel requested, ignoring.
‘subsystem’ channel request for ‘sftp’ subsystem.
using SFTP protocol version 3 for this session (channel ID 0)

You can also save new files.
When I save a file, the log shows:

using ‘/etc/proftpd/ssh_host_ecdsa_key’ as 256-bit ECDSA hostkey
sent server version ‘SSH-2.0-mod_sftp’
received client version ‘SSH-2.0-FileZilla_3.54.1’
handling connection from SSH2 client ‘FileZilla_3.54.1’


mod_sftp/1.0.0: user ‘xxxxx.com’ authenticated via ‘keyboard-interactive’ method
unsupported ‘simple@putty.projects.tartarus.org’ channel requested, ignoring
‘subsystem’ channel request for ‘sftp’ subsystem
using SFTP protocol version 3 for this session (channel ID 0)
error resolving ‘/public_html/start-test.php’: No such file or directory

But the file has been saved in any case.
Now I’m trying to update the file.
Then the question of action arises.
I choose to overwrite.
Then it comes in the log file:

OPEN command for ‘/public_html/start-test.php’ blocked by ‘STOR’ handler

The new file is not saved after 3 attempts.
If I delete the old first, then I can save the new:

error resolving ‘/public_html/start-test.php’: No such file or directory

I have searched the forum but found no explanation.
Please help. How can I solve this?

Does this work for everybody else?
Am I the only one with this problem?