Woocommerce Subscriptions Translation issue

I need to translate woocommerce and woocommerce subscriptions plugin into German. I’m using POEdit and placing the .po file in wp-content/languages/plugins/woocommerce-subscriptions-de_DE.po then compiling it to the .mo file.

The translations work mostly fine but some strings just dont translate. for eg. there’s an issue whereby $97 / month doesn’t translate into $97 / Monat. Is this a known issue and is there a fix for this?

The .po file contains entries for:

year –> Jahr;
month –> Monat;
day –> Tag;

The function responsible in class-wc-subscriptions-product.php is

$subscription_string = sprintf( _n( '%1$s / %2$s', ' %1$s every %2$s', $billing_interval, 'woocommerce-subscriptions' ), $price, wcs_get_subscription_period_strings( $billing_interval, $billing_period ) );

I’m using Woocommerce subscriptions Version 2.0.11 and Woocommerce 2.5.5.