My CSV import failure solved

There's a lot of posts about failures when importing CSV files.

I found a solution to my specific problem I hope will help others.

I had issues importing small CSV-files ( 100-200 lines ). The import stopped
after the first batch eg. 23% and stayed in running state only fixable by
resetting the state in the database ( or applying the patch adding unlock buttons ).

I was able to run the import in background mode with cron.

I finally realized that this was caused by conflicts with the sites theme and
after adding two rules to themekey forcing the related pages to the
administration theme ( we use Seven ) the import worked.

My rules are :
drupal:path = import/my_feed_name -> administration theme
drupal:path = import/my_feed_name/% -> administration theme

We use the same method to force IMCE related pages into the administration theme as
IMCE is known to conflict with the css in a range of themes.