[pre-release] Import Page: Changes in loaded file are not considered in further processing

[TheAxelander]

Describe the bug
Changing content in the loaded file is not being considered in validation process

To Reproduce
Steps to reproduce the behavior:

1. Go to Import Page
2. Import a file
3. Remove a few rows
4. Follow import process until Validation

Expected behavior
Only the content visible in the preview is considered during validation process

[TheAxelander]

Unable to reproduce