Due to a bug in macOS Catalina, installing dynamic wallpapers is a little bit different and we hope to see it fixed in the upcoming macOS Big Sur.
Thanks to our community there is a solution that seems to work most of the times:
Your wallpaper adjusts to the current Sun situation at your location.
This mode reproduces the exact sun conditions according to when your photo was taken. This also takes the seasons into account, meaning: In winter, the wallpaper will automatically choose a lower sun than in summer for example.
Sun mode only works if proper GPS/EXIF data is included in your image file. The Dynamic Wallpaper Engine automatically checks if EXIF data is correctly included in your files. If not, we recommend using https://thexifer.net/ to edit your EXIF-data. Be sure to check whether your file includes
Your wallpaper adjusts to the system time of your Mac.
Super simple! Choose a timestamp for each photo and it will be shown to the system time of your Mac.