As mentioned in the Craft CMS docs, file-based mutex locks don't work reliably in load-balanced environments. This is due to the filesystems of each node in a load-balanced setup being isolated from one another.

As Servd is indeed load-balanced, we force all projects to use the Yii Redis driver to store mutex locks. This will override any project specific config that is checked into your repository and thus avoids any issues around this area.

If you have specific mutex storage requirements, feel free to open a support ticket to discuss with us further.