Hi Antoine,
The issue is the one reported in this article- https://www.veritas.com/support/en_US/article.000125834.
Basically a user could download a large file, several hundred MB or bigger, and this would cause all of the SMB threads to be allocated for that file. Since no SMB threads are available any user trying to browse shares on the file server would only see that the server is not responding and folders/files are not visible. This should return once the download completes, however this could be several minutes depending on the size of the file. A similar issue could happen with mass recalls of files by users.
This update modifies the agent so that the SMB threads are not exausted and users should be able to browse without issue. I have tested this in the lab where previously the issue was present and could no longer reproduce the issue. The 12.2.x release of the agent also removes file blocking as this is no longer supported. I would highly suggest the new agent if a similar issue is being seen.
I hope this helps.
Regards,
Patrick