Hi,
Before the 2.6.2, when the current language on the website was not supported by the CM-CIC ('fr','en','de','it','es','nl','pt' are all supported), the plugin was directing to the CM-CIC interface with the French language.
But it's more logical to display the payment page in English in such case since English is more widely known than French.
So we changed the default language to be English in such cases.
We didn't expect that it could be a problem for the CM-CIC.
You can always change the line:
$localeCM = 'EN';
to:
$localeCM = 'FR';
in the file plugins/hikashoppayment/cmcic/cmcic.php
if you want to get the behavior from before.