Nested Override Symbol doesn't populate
**Which version of the plugin are you using?**
 [3.0] Data Populator for Sketch

Question:
Thank you for making this plugin! It's saving me a ton of time getting this set up! I have a few questions about this limitation...

I'm working with a shared library where I'm placing my symbol. My symbol has a background and a symbol inside to dictate how many digits in the number field. I have it named "1 digit" with option to override "2 digit" and "3 digits", my JSON is called {one} {two} {three}.

What I'm trying to do is create a Table Cell. Each cell has the option of selecting the number of digits plus the styling. When I have the base symbol placed in my file, JSON would successfully override the symbol for what's placed as default, 1 digit. 

If I override the symbol, ie. "base was 1 digit, I override it to 2 digit", the JSON will no longer populate. There's also something strange about, if I made the base 2 digits, then override it to 1 digit, it will remove 1 number as it increments down, but would not be able to repopulate if it's switched back to 2 digits.

Am I doing this wrong?

Example to illustrate below:

![screen shot 2018-10-20 at 2 52 37 am](https://user-images.githubusercontent.com/11272475/47252445-44e31500-d413-11e8-8fa9-5ec15a841580.png)

![screen shot 2018-10-20 at 2 55 14 am](https://user-images.githubusercontent.com/11272475/47252464-95f30900-d413-11e8-990c-6264fc59aa01.png)

**Environment (please complete the following information):**
 - macOS Version: macOS High Sierra 10.13.6
 - Plugin Version 3.0.0
