Hey There,
Thanks for writing in!
Please try testing for a plugin conflict. You can do this by deactivating all third party plugins, and seeing if the problem remains. If it’s fixed, you’ll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.
If this doesn’t help, deactivate Revolution Slider and Envira Gallery one by one see if this helps.
Let us know how it goes!