This is a problem due to how the iOS WebView works. Once the scanner is started the keyboard is automatically closed and can't inject any data once the scanner closes. This is something the Keyboard Wedge can't influence due to restrictions by Apple.
As this issue can't be fixed by us, we recommend using the Barcode Scanner SDK for the Web or using the Web Wedge Feature of Scandit Flow (which provides a container app to access the webpage through which can work around said issue) to scan into web pages.
Android and Windows are not affected by this problem.