Thanks for reaching out. We are sorry for the trouble with Lightroom. We are here to help!
Could you please share the Lightroom version and the operating system you are working on on the mobile device(Android/iOS)? Do you notice any errors when you change the cameras? Have you tried any troubleshooting steps?
Please try to reinstall Adobe Lightroom after confirming that your images are synced on Lightroom web (https://lightroom.adobe.com).
Please share the screen recording of this behavior to help you better.
Let us know if this helps!