MacBook Pro and Finder recognize new iPhone 11 Pro Max, but can't browse or transfer files to it.

Hi there,

as the title suggests, the Finder of my MacBook Pro (MacBook Pro (15-inch, 2018) on macOS Catalina 10.15.4 (19E287)) recognizes that my new iPhone 11 Pro Max (iOS 13.4.1) is connected via Lightning cable, however I cannot browse or transfer files via the finder. It just gives me a message that I could restore my iPhone if there were any problem with it, which I really don't want to do as I have just set it up (which was a hassle in itself, because I am coming from an Android phone and the supposedly easy transfer via the app "move to iOS" just didn't work).

Same problem in iTunes. It just says "The device wasn't found", although clearly it shows up.

I have "untrusted" all devices, reconnected the cable and trusted the MacBook Pro again. Then it briefly shows that the phone has 490 GB of storage, before it switches to 505 GB. It feels as if it is about to let me access it via Finder, but then gives me that message as shown in the screenshot below.

I have attached screenshots from both Finder and iTunes. Any help is greatly appreciated.

Thanks.