Error when searching subscriptions in backend

-- HikaShop version -- : 4.4.0
-- HikaSerial version -- : 3.1.1
-- Joomla version -- : 3.9.21
-- PHP version -- : 7.4.11
-- Browser(s) name and version -- : Brave - Versione 1.15.72 Chromium: 86.0.4240.75 (Build ufficiale) (a 64 bit)
-- Error-message(debug-mod must be tuned on) -- : 1054 Unknown column 'hk_user.user_email' in 'where clause'

Hello,
When I use the search field in the subscription listing I always get the error

1054 Unknown column 'hk_user.user_email' in 'where clause'

The page gets frozen on the error message and I have to delete the cookies and login again to unblock it

Thanks