In most cases it is due to the PC having to little RAM and or too slow a processor. Can you give some details of your PC/MAC. A good tool to use is Speccy which when you run it will show much about your PC. Please note the minimum PC resources quoted by Magix are not anywhere near enough to run Magix PhotoStory smoothly.
My last PC far exceeded the requirements but it took ages to load Photostory and editing was slow jerky with the program often crashing.
Assuming the computer is running Windows 11, is OneDrive actively backing up your Documents folder to the cloud storage?
To determine this, in Photostory select File, Settings, Program Paths tab, if you see 'OneDrive' in any of the options then this may be the cause of the issues you are having.
If this is the case, you need to stop OneDrive syncing the Magix folder and subfolders, see this article on how to do this.
. . . . Speccy . . . .
This app, like other similar apps, provides a lot of superfluous information we do not need. See this topic for what is required. I would suggest you put the information in your Signature for future reference, see my Signature link is below.