unable to set ipv6 DNS after latest firmware upgrade

Just registered an account in order to report this issue and found this thread. 

I have run into exactly the same issue like the screenshot shows. My devices can get IPv6 address. But, they don't work at all. I thought it could be the ISP DNS issue and want to try a different DNS. When I manually configure DNS and applied the setting, it shows undef and non-readable characters like the screen shot shows. Did 2 factory reset and follow exactly the same procedure. It is still like that. It feels like the data was not stored properly or the read function didn't parse the setting correctly. 

It seems the whole IPv6 feature broken on my device. Please fix it.