100% sure. Once I rolled back the site to a previous backup (before plugin was installed) all was fine and is up and running again. For some reason the plugin caused a server resource overload, the site went into 508 and hosting provider confirmed that once installation of plugin was reverted, the issue stopped. All started when I wanted to watermark about 40 images. Don’t know if the bulk watermark of so many images caused this but not trying again.