VFX subgraph cannot be opened after second import and deletion if VFX is not open

How to reproduce:

1. Import the attached package
2. Open CandleData subgraph and CandleFlamevfx.vfx
3. Delete Candles_Candlestick, Card, Environment folders
4. Import the package again
5. Open CandleData subgraph

Actual results: Subgraph doesn't open

Expected results: Subgraph window opens

Reproducible with versions: 6000.5.0a2 (test trunk only)

Not reproducible with versions: 

Can’t test with versions: 

Tested on (OS): macOS

Notes:

• If we open a VFX window first, then we can open subgraph windows as well
• Marking as minor issue as it requires second import and has a workaround