Girocard (debit card) or ELV (eletronic direct debit) transactions are only cleared after the payment terminal has done the end-of-day report. Most commonly payment terminals are configured for automatic end-of-day reporting. Otherwise you need to start this process via the secuconnect API.
You can do the end-of-day report calling POST /api/v2/Smart/Transactions/me/EndOfDay:
POST /api/v2/Smart/Transactions/me/EndOfDay HTTP/1.1
Authenticate: Bearer qb56tjj1bcvo9n2nj4u38k84lo
This request is blocking. Secuconnect API only answers after the payment terminal has finished the end-of-day report.
If everything is fine, the API responds with 200 OK and the representation of a Smart Transaction thet tracks the end-of-day report.