When the 'Combine assets' feature is enabled, it's not uncommon to experience issues, errors or conflicts especially about the Javascript loaded on pages. In most cases this is due to the change in the order of execution of scripts included by various extensions that have been installed on the Joomla! website.
Additionally you could experience issues about CSS styles applied to the page, indeed the order of overrides for CSS could be shuffled in a different order.

To handle and solve this kind of problems, JSpeed has a powerful system to manage inclusions and exclusions of assets that should not be included in the combined file.
When you choose to exclude a certain asset from the combined file, it will be extracted and listed in the page source code normally, thus preserving the correct order of execution applied when the browser is going to parse the HTML code.