If that does not help, please give more information on how you are adding the images to the timeline.
Also check if they are on the timeline in Timeline mode and/or can be added.
What is the specification of your computer system including Windows version and program version, see this topic for what is required and please quote processor and graphics card make/model in full, and also what monitor/screen resolution(s) you are working with if this is a laptop.
I would suggest you put this information in your profile signature so we do not have to keep asking for it.
Thank you for your response. My problem arose after a photostory that I was working on froze. After I ended the photostory "task" in task manager and reloaded the photostory, the photo images for that project could no longer be viewed in the phototrack in storybook mode but they continue to be seen in the monitor. If I add a new photo to storybook mode it appears in the phototrack. There is no problem viewing objects in timeline mode. More baffling is that everything works fine if I create a new project This problem is unique to this one project that froze. I can simply create a new story with the photos but I'd like to know what is causing this problem so I can avoid a repeat. I added my computer specs to my signature.
The freeze and closing Photostory using Task Manager has probably corrupted the project file.
You may find there are some backup files of the project in the same folder where the project was saved, they will have _BAKn.MP_ after the project name and n = a number from 0 to 9. the file numbers cycle through 0 to 9 after which the cycle begins again starting from 0..
Work through loading the backups using the date/time the file was created to determine the latest, until you find a good one that allows you to continue adding images.
Check the the intel UHD 630 drivers are up to date - the latest version is 31.0.101.2134 avaialble from here.
. . . . NVME AD 238 GB . . . .
How much free space is there on this disc, you need at least 15% preferably 20%?
Are the project files and images on an external USB drive? If so the freeze may have been caused by the drive going to sleep and not waking up quick enough, and/or the USB ports were powered down by Windows.