We're sorry about the trouble with Lightroom mobile. Would you mind sharing the version of Lightroom mobile you're using along with the version of Android you're running? Since when are you experiencing this issue?
You can try clearing the cache for Lightroom mobile by going to the Settings of Lightroom mobile, then Device info & storage. If you're using the app through a subscription you can also try re-installing the app to check if that helps. If you're using the free version of Lightroom mobile, please backup your images & preferences prior to re-installing the app.