The signal is a 1 pulse per second PWM signal, pulses are 100 or 200 ms wide (it's DCF77).
I don't see any data scrolling through the first division pre-trigger. It's just the previous data which appear frozen.
When I setup my scope anew it works as expected, but after I loaded the .psdata file the 30 seconds blackout returned (only it's now 40 seconds, whereas the 30 seconds I had before were rather consistent). Neither closing and reopening the program, nor shutting down and repowering the scope seems to help.
I set the timescale to 1ms/div and then triggering seems normal, but when I go up from there the blackouts return: about 5 seconds at 200ms/div, 15 seconds at 500ms/div to 40 seconds at 1s/div.
I also tried triggering on a faster signal (several kHz), but also then the 40 seconds blackout remains at 1s/div.