When a transfer is initiated with any ING bank, it may appear stuck in a processing status such as "RCVD", "ACTC" or "PDNG". A full list of statuses can be found on ING's Developer Portal here.
These processing statuses mean that there are pending actions required from the consumer's end. Once the PSU(s) takes an action i.e. approve or decline, the status will update accordingly.
After 10 days, the bank removes the transaction if it's not confirmed by the PSU.