Plugin doesn't work with replaced nested symbols
**Which version of the plugin are you using?**
[X] Data Populator for Sketch
[ ] Data Populator for Adobe XD

**Describe the bug**
I have a symbol that contains nested symbol, which in its turn has text layers with the JSON keys to be populated. Everything works as expected, until i replace that nested symbol with another one, which has similar structure and same text layers with JSON keys that needs to be populated.

Once i replace, plugin doesn't populate those text layers.

**To Reproduce**
Steps to reproduce the behavior:
1. Insert symbol containing nested symbol with text layers that has JSON keys.
2. Replace nested symbol with another one, that also has same text layers with JSON keys.
3. Populate
4. Nothing happens

**Expected behavior**
Expect to behave same way as with original symbol.



**Environment (please complete the following information):**
 - macOS Version: 11.0.1
 - Sketch 70.5
 - Plugin Version 3.6.0
