I'm experiencing a similar issue with the Moodle Desktop app. I have a link into an Announcement targeting a Page Activity into another topic (https://mysite.com/mod/page/view.php?id=27)
On the Moodle Desktop app, when I click on the link the app brings me to the activity (as you said), but in between the two views I get the error message "Error getting activity data".
Any suggestion? Many thanks.