Hello, good day.
I had the same problem, but I use multisite.
I solved the problem with the following steps:
1) I went back to version 3.4.9 using Wp-rollback.
2) I disabled the plugin on the network.
3) I entered the specific site and activated the plugin there.
I followed the steps in this link: https://www.icegram.com/documentation/es-how-to-install-and-activate-plugin-single-multisite
