Hello Chris,
Thanks for reaching out and I’m really sorry about your issue with the selector.
First you can check if the same thing happens if you switch to a default theme like twentysixteen. If it works well with that, then most probably the theme developer will be able to help you.
It might be also worth running a full test for conflicts, maybe one of the other plugins you use interferes with it.
I hope this helps. Let me know what you find.
Also, if you will need further help from us, then please share with me your system information.
Thanks and cheers,
Andras