I have been having a problem for a few months on Samsung S8+ (Android 8.0) where I type in a few letters of a site name to filter the result list from my vault. When I tap on the desired item, nothing happens i.e I don't visit geekfell get a menu of operations popping up.
If the list is not filtered and I scroll down to the item, then there is no problem.
The problem doesn't happen all the time, but certainly 4 times in 5.
Could you try uninstalling the LastPass app, restarting your device, and reinstalling the app to see if it resolves the issue with the selected site not properly being filled from a filtered list?