An odd behavior that tripped me a few times is that when exporting files using an Export Preset from the Context-Menu (Right-Click -> Export -> ) any export plugins specified for that preset are not run. Doing the export by choosing Export... from the main menu or context menu and selecting the same preset, runs the export plugin. This is annoying because if I forget than an export has a plugin, then I must export again and tell Lightroom to overwrite as there is no way to just run the plugin on the files which were just exported.
Is this expected? Most importantly, is there a workaround to get export plugins to be run every single time one does an export with the preset that specifies it?