"error: DwWef script exception" when using certain insert options...

I keep getting the following error...

error: DwWef script exception

I'm using Dreamweaver cc 2017. The error occurs when trying to insert specific features.

In one instance, it was the header H1 tag, and in another instance, it was a responsive image (default). So far, it's looking like any insert menu with a drop down menu for some reason... 0_O

Can somebody help me fix this? It is getting in the way of completing an answer to my other topic...