That looks like a problem indeed, have you tried exporting without merging the blocks?
Viewing post in Exporting issue
I have. I tried to export without merging and with textures, without merging and without textures, and with merging and with textures. Sadly, I've gotten the same results. I am going to start peeling away my custom blocks and see if I can link it to something specific that causes the problem. Thanks for the reply, I love this tool and the assets!!