Apologies for the delayed response. Thanks for reaching out. Would you mind sharing the version of OS? Also, please share more details about the issue. You may share screenshots or a small video of the workflow. It'll help us understand the issue better and answer accordingly.
If you are using Windows 10, you should be able to see the preview of .Ai files in Preview pane. You may also install Adobe Bridge for thumbnail preview. Please check out more on https://www.adobe.com/products/bridge.html