Thanks for reaching out.
We are sorry for the trouble. I’ll need more information so that I can help you with this issue.
Could you please share the exact version of Lightroom from Help > About Lightroom and the operating system you are working on? You can log on to Lightroom Web (https://lightroom.adobe.com) with the email account on your mobile to check all the synced images that should be the same when you sign in on the Lightroom Desktop app using the same email account.
Please ensure Lightroom Desktop is up to date via the Creative Cloud desktop application. Check this for help: https://helpx.adobe.com/lightroom-cc/get-started.html
The interface on Lightroom Desktop & Lightroom Mobile is slightly different. Please check this to get started: https://helpx.adobe.com/lightroom-cc/using/masking.html
We hope this helps,