Hello,
If you want to have a automatic renewal, you need to use a recurring payment plugin, such as "Paypal Recurring".
In the HikaSubscription configuration, there is an option to make the recurring optional ; so if a customer have a subscription product in its cart, he will be able to pay with regular payment methods and not only with recurring one.
Depending that setting and the payment methods you have configuration, it could explain your issue in the checkout.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.