Hi @hoppel118 and @ellnic
We were able to recreate this issue. Looks like the forum admin has done something to the latest plugin set up when the App tries to get topic from the forum, the forum's server throws back a 500 internal error.
I'll send a note to the forum admin to see if anything has been done recently. I'll ask if they could send us any error log there may be associated with Tapatalk usage. PHP, web service and the application log. See if you could request the same. Thanks.