Cannot parse response ( iPhone SE )

I am getting following error message whenever I am going to save the songs “ cannot parse response”. I contacted the app developer (app name - ‘Smule sing’) & they informed me that it’s not app related issue & it’s iOS issue. I installed the same app in an android phone using my login & didn’t face this issue. This issue is happening only in my iPhone.

(I already tried every other options like restoring my phone but it didn’t help to resolve)

Please please please help please. Thanks in advance.