Apns certificate installed and CA Signed - now Windows and Linux Spark client (2.6.3) cannot connect

I managed to get our client’s iOS Developer - Push Notification Certificate installed and “CA Signed”. See apns certificates and keytool - Recipe for details.

However, now our Windows Spark Client 2.6.3 refuses to connect with “Invalid username or password”

Using C:\Program Files\Spark\jre\bin\javacpl.exe under the Security tab > Certificates button, I added quite a few of the Apple PKI Certs

but it hasn’t helped.

Does anyone know if and how this can be accomplished?

Thank you for your time.