I guess it’s could happening because some conflict of our gallery plugin with some other plugin or theme on your page.
In the case if you update your page plugins / theme during weekend it’s could be a reason of such gallery behavior. Maybe you installed some new plugin which have some images related functionality or some java script libs included. As result you could have such strange gallery behavior.
As solution you can try to use compatibility settings of the robo gallery. When you open admin section on the left side menu you can find robo gallery / settings section.
When you open this section you can see JQuery version option. Try to switch value to Forced include, save gallery settings and check results.
Try to clean cache before page with gallery re-load.
