So your browser can actually cause a lot of really random and annoying problems when it comes to working on your website. With that in mind remember in the future that clearing your cache can fix a number of other issues as well visual editor buttons not showing up. In short, the cache is made up of temporary files that your browser collects while you do your online tasks.
Leoemery has a great overview of what a cache is here
https://my.wealthyaffiliate.com/leoemery/blog/so-w...
1. Check in a Different Browser
This is the quickest way to see if there is a browser issue. If you have no problems in Internet Explore but it isn't working on Chrome then I would try clearing your cache
2. Check on a Different Computer
I have a computer and a laptop so when I have weird problems I check in the same browser on both computers, this can also be an easy way to check if it is a website issue or a browser issue.
3. Clear your Cache for your specific browser
I know that a lot of people use a lot of different browsers. Since my time here I have heard of a number of browsers that I have never heard of let alone use, so with that being said I cannot help you on clearing cache.
Here is some training from with Wealthy Affiliate about cache clearing for Firefox and Chrome (again from Leo)
https://my.wealthyaffiliate.com/training/how-to-cl...
If your browser is not one of the ones above then you should be able to perform a simple Google search on how to clear the cache for your particular browser. Or if someone can find a training/blog in WA about how to clear that particular browser cache feel free to leave it in the comments and I will update this post with it for easy access to others.
Even if for some reason the problem does not go away when you try in it a different browser, it might be a good idea to clear your cache anyway. Sometimes things can surprise you.