Slider has issue after a while (couple days or hours after publishing) - WordPress

When you see problems happening after a while without touching anything, these are always cache caused issues, like a caching plugin or server cache created problem.

When you publish a slider, we are always using the same exact code, so from our end this code doesn't changes, that is why the error can only come from somewhere else. 

If you go to the admin area to clear our cache or save on a slider, our code triggers a WordPress post saving action. Most caches are refreshing automatically when this happens, so this is why it might looks like as if our code would fix the problem, but actually the cache clearing of the caching plugin/server cache fixes their wrong automatic code. 

So to debug where the problem comes from, you should go to your Plugins list and turn off any cache/optimization plugins you have. If the problem comes back, you should contact your server host, as if it isn't a plugin caching your website, it can only be the server's cache, and you could ask them to turn that off.