try modifying login.htm under your WF package/pub directory so that “?timeout=600” method=“POST” is appended to it if its not there already
e.g., <FORM ACTION=“/web/WmWFServlet/wfservlet?timeout=600” method=“POST”>
Its also mentioned in the Workflow Users Guide\Servlet parameter section.
Also make sure that the jvm version is supported by WF 6.0.1 and its not been changed, if JVM version is different you might see this behaviour.