Renaming custom symbols affects asset values
### Expected Behavior
Renaming a custom holding's symbol should not affect its asset value.
### Current Behavior
I imported a csv file, and after successful import, renamed the holdings from APIR codes to more user-friendly names, eg. renaming "YOC0100AU.FundAU" to "Australian Unity Property Income Fund". This caused the asset values of all renamed holdings to become $0.00, even though the transaction and price history were still correct.
### Possible Solution
<!--- Not obligatory, but suggest a fix/reason for the bug, -->
### Steps to Reproduce
1. Upload a csv of transaction data via Add investments>Import from broker/account>Upload your own spreadsheet>Custom investments
2. Rename one of the holdings
3. Holding value in portfolio screen will be displayed as $0.00
4. Renaming the holding back to its original name restores correct value.
### Context (Environment)
I was trying to add a more user-friendly name to all my holdings.
Issues