Sharing violation

Hello

Since a while it was impossible to save Excel file on my C drive but it is working on a D drive. In same time Excel filed culd be openned only on read only mode.
After few trys it seems that the anti ransomware is preventig to rename the temporary file during the save process.
Is it a known issue. How to correct without suppressing the anti ransomware functionnality ?

I have Avast 17.5.2303 version

Thank you

Ransomware Shield - FAQ: https://www.avast.com/faq.php?article=AVKB50

Ransomware Shield = Firewall for your Files
Just like with a firewall if you want to grant access to the file you need to grant access through the Ransomware Shield.
Without granting access, the file is locked and protected against change.