SEO friendly URLs with multiple languages enabled

Version: 3.70
Issue: Unique SEO code is overwritten/lost

Expected behaviour:
1. Viewing http://www.yourStore.com/en/nike
2. Changing language with language selector
3. Redirects to http://www.yourStore.com/cn/耐克

Current behaviour:
1. Viewing http://www.yourStore.com/en/nike
2. Changing language with language selector
3. Redirects to homepage with URL http://www.yourStore.com/耐克 (SEO code "cn" disappears)
Only happens with 2 Chinese words (have not tried 1 word). 3 or more words works as normal, so is changing Chinese (/cn/耐克) into English (/en/nike).

Thanks a lot for reporting! We'll investigate it (work item)