inkappointment pro "add custom field" not working

I'd like to add a textarea field allowing people to provide their address.
However, trying to add a custom field does not work.
On submission of the form for adding the field I get an alert saying that the data be posted through an unsecure connection and could possibly be read by unauthorized people.
The submission allowed nevertheless, it returns to the "add custom field" form without showing any created custom field. In other words: I had not been created.
I have this blog on https. Is this perhaps the reason why it doesn't work?
Would be strange, but help would be appreciated.

Regards
Wolfgang

 

Kindly, share your WordPress admin credentials at [email protected] along with this thread URL:

WordPress site login URL:
WordPress admin username:
WordPress admin password:

We will check and do the needful.

Warm Regards!
Naveen Kolhe
InkThemes.com

 

Many thanks for caring, I just sent the login details to your email a few minutes ago.

 

Hello Wolfgang,

Could you please resend your credentials, I was unable to find it on our email account.

Please share your thread URL with your credentials, so that we can search it easily.

Warm Regards!
Naveen Kolhe
InkThemes.com

 

my sender address was [email protected]