I`ve Tried so many Options, like changing the the file Extension
It is probably an anti-ransomware setting somewhere
Mac
You probably need to give LibreOffice full disk access from System Preferences > Security & Privacy. See this site on how to do it if you aren’t sure: Explained: What is Full Disk Access & Full Permissions on macOS Mojave .
Windows
If you don’t have a third party anti-virus have a look at this: Defender Controlled Folder Access
Turn Off Defender
Select Start > Settings > Update & Security > Windows Security > Virus & threat protection.
Under Virus & threat protection settings, select Manage settings.
Under Controlled folder access, select Manage Controlled folder access.
Switch the Controlled folder access setting from On to Off.
If you do have a third party anti-virus go into settings and then look for something like anti-ransomware or folder protection. Have a look at the blocked apps list, if you see soffice.bin in there change it to Allowed (you might have to read AV help if not obvious). Otherwise go to the Allowed Apps setting and allow soffice.bin, this might not be easy so you might have to add the different LibreOffice executables (Calc, Writer, etc.) to the Allowed list. Note that 3rd party anti-virus might make files Read Only so you can create a new file but you can’t save it subsequently. Sometimes, you might need to reboot after allowing a program access.
Cheers, Al