@George It’s very easy to replicate.
- Create blank project - NodeJS, Docker
- Add some blocks to index.ejs - Image Features for example
- Add Select component
- Go to Select Component - Data source
- Switch to code
- Click Cancel
- Turn off “Toggle App Connect Mode”
- Preview is broken
Sad to realize but there was several topics mentioning this issue with detailed replication steps- Bug Report - nothing displays in Design View and Design mode losing style but got no proper attention from Wappler developers.