Slideshow conflict

I created a site using this theme in 2012 and all has been well until recent updates to Wordpress core and plugins. Now the slider plugin I'm using doesn't work; the first image is displayed forever and it never rotates to the other images.

I switched to a default theme (Twenty Fifteen) and the slider started working immediately.

What might I be able to do to make this theme compatible? If even you could give me some suggestions that would be super.

Hi!
Current version of our themes is 2.3. It is fully compatible with the latest version of WordPress. You would better use the latest version of a theme. But don't forget to make a backup.

Thank you very much for the reply.

I had no idea the theme had been updated...there have been no notifications within Wordpress.

I have already fixed the problem, for now, by finding a different slider that met my needs that also didn't have compatibility issues. But should more problems arise, updating the theme is where I'll start.