Hi, I am an Independent Advisor, and welcome to Microsoft Q&A.
Let me help you with this issue.
I understand that your picture files are not showing the correct icon inside the Picture folder.
Please follow the steps below.
On the Picture folder, please open the Folder Options by following the steps below.
Select the three horizontal dots located on the right side of the ribbon tabs, then choose Options from the list.
When the Folder Options window appears, make sure Always show icons, never thumbnails is not checked.
After that, click Apply, and then select OK to confirm the changes.