When I make a slideshow, I start by using the Photostory wizard to import my media and specify the basic settings (effects, length, etc.) to be used. (I typically set my effects level to nearly high. Then I save the project, close the wizard and use the timeline view to add/fine-tune effects and other things as needed.
When it comes time to export to an MPEG-4 video, I do so using a custom preset (I forget which preset it's based on ATM, I'll get back with yall on that when the export in progress finishes) at 3840x2160 resolution, 60 FPS (not 59.94), Progressive Scan and hardware acceleration (in Advanced options) enabled. Everything else at default values. (including the computation of effects being done on the GPU)
But.... here's the thing. In the title bar of the progress window, it says "Mixing down...(no hardware acceleration)" despite me having it enabled in the render settings, as well as everywhere I see it in the program settings.
So what am I doing that's causing this behavior? How can I force it? Right now I'm in the middle of an export (of about 11 minutes of video) that's been running since 12:00 PM EST today, and I'm estimating the total export time to be about 9 hours total at most (I'll bet it probably would've taken about 3 if it wasn't done solely on the CPU).
Hardware and software I'm using:
--GIGABYTE B260M-DS3H rev.1.0 (Motherboard) (Latest BIOS version as of this post)
--Intel Core i5 7500 @3.4GHz
--8GB RAM
--EVGA GeForce GTX 960 (latest drivers as of this post)
--Windows 10 Pro (latest version as of this post)
--MAGIX Photostory Deluxe 2018 (latest version as of this post)