Normal behavior would be to read document from document cloud in web browser, then re-open in mobile app and continue reading from where you left off, the app will remember the last position from web browser.
This works in android devices, I can read in web and continue reading in mobile, or between devices. But in iphone it will not continue in the last position, it will only continue from where it was left off in the iphone device.
Please help, this used to work in 2018, but since then it hasn't and I've kept checking every update in my iphone.