I forgot this when the problem disappeared, but now we stuck with this issue in another environment, running recent version of Odoo 10.0. Our customer finally solved the problem. We tried to import data from excel, using csv + UTF-8 encoding.

MS Excel generates UTF-8 BOM marker to the beginning of the file, and because of that, Odoo fails to identify the first field as "id".

IMHO this is odoo import bug, if it does not cope with UTF-8 BOM for UTF-8 files, but workaround is take the data e.g. in windows character set, then import works just fine. 

Put a slash "/" in a header (you way want to add fields name but it works without). No need to add datas in the column.

This is not really an answer to original post.

How I manage my Visa each month... 

I download the ofx on AccesD (ofx quicken, conciliation bancaire carte) :

I import it :

I reconcile. Note that total of 0 $ each month end.

My account chart :

We have an account for each Visa card. And we have a main account. Each month, total is transfered to the main account. When we pay the visa with an other bank account, payment is also transferred to the main account. So, when the Visa is paid, all account in the chart should have a balance of 0 $.

We don't download any statement from AccesD for our bank account. We don't use this account for our business (to many fees...). But I have checked, and like you said, it seems that this is only possible to download a CSV file...  

I'm with Odoo 10 community. Until 5 minutes ago, the checkbox was always enabled and I was unable to un check it. But now, it's unchecked and I can't re-enable it.

@Pascal Tremblay, I'm using this module to import Desjardins bank account statement. It appears to me that I need the relation fields (mostly those in the line statement section) to import line description (ex. check), line reference (ex. check number), line credit and line debit (Desjardins csv splits them in two column instead of negative numbers). My case is not as complexe as yours. Did you manage to import simple Desjardins statements without relation fields?