Three Problems that occurred at about the same time

This notice is received when I save any new document and I have requested no protection or lock. There is plenty of space on the disk. The message says a lock file cannot be created but the document is locked into read only. Note that the file is locked but the notice says there is not permission to lock the file??
What may I have unknowingly done to cause this?

The notice: “The lock file could not be created for exclusive access by LibreOffice, due to missing permission to create a lock file on that file location or lack of free disk space.
Select Notify to open read-only and get notified when the document becomes editable.”

BUT, I can save any document to Desktop and then copy that file and paste it into the folder that would only allow a locked file to be saved.

This is a Win 10 computer. I reinstalled Libre Office and the problems remain.

Does this appear to be a Windows or Libre error?

Additionally, when I click “New Folder” I often get “file not found”

When I create a new .odt file and try to save it in my C: documents folder I get the error message “File not found”, as if I was trying to open a file.

Add soffice.bin, probably in C:\Program Files\LibreOffice\program\soffice.bin, to your anti-virus Allowed List.

C:\Program Files\LibreOffice\program\soffice.bin, to your anti-virus Allowed List.

I can get to ***\program\ but there is no soffice.bin there. In the window to add programs to be allowed by the antivirus there is a soffice.bin file somewhere. I added that filename to the allowed list but it had no effect.
Is there something more I can try?
Thank you for your help

Navigate from the anti-virus dialogue to *C:\Program Files\LibreOffice\program* and start typing in soffice.bin, the AV program should add it OK.
You might need to restart something, I think with Avast/AVG you had to restart Windows.

Note that each time you upgrade to a new version of LibreOffice you need to add soffice.bin to the Allowed List again.