Session log file is empty for fortinet type devices while the remote connection is still active

[cbuons]

Description of Issue/Question

Since updating to 4.3.0 (from 4.2.1), we've noticed an issue wherein the session log file is not written to until the remote connection is disconnected. This issue has only been observed on fortinet device types so far (due to our environment, though it may occur on other device types). In the past, we would tail the session log to monitor the read/write activity while executing network automation scripts since it was a "live" view of the device CLI, and allowed our engineers to watch for any unexpected activity or errors.

This issue has been reproduced on macOS 14.3, Ubuntu 22.04.3, and RHEL 7.9. Our current workaround has been to revert back to netmiko 4.2.1 for now.

Setup

Netmiko version

(Paste verbatim output from pip freeze | grep netmiko between quotes below)

netmiko==4.3.0

Netmiko device_type (if relevant to the issue)

(Paste device_type between quotes below)

fortinet

Steps to Reproduce the Issue

Send any batch of commands and follow the session log with `tail -f <PATH-TO-LOG>`