I am importing inventory totals through a CSV

My CSV has the same headings as the recommended heading

my CSV has quantities in ON HAND and AVAILABLE

but when importing - all totals get set to 0 (ZERO) and has wiped out all my stock

the only items left have a minus number

I do get error messages when importing - but they are code errors -(for lack of codes) not number errors

Also the import takes over 6 hours to run - on the screen - but the email confirmation (saying its imported) comes through in 6-8 minutes