As more and more devices are being shipped with Android 10 we are increasing getting reports of problems with beacon apps built for previous versions of Android. We mentioned this issue back in October last year.
To compound the problem, many popular Chinese manufacturers such as Oppo, Huawei and Xiaomi also now using Android 10 in their forked versions of Android. Not only are these manufacturers inheriting the Android 10 problem but their devices also suffer from problems running services, such as Bluetooth scanning, in background. The problem is that these manufacturers also add their own additional background throttling (and killing) mechanisms into the OS that make Bluetooth unreliable. The site dontkillmyapp documents the known problems and some workarounds for various forks of Android.
If you think you might be a victim of these issues, try using another, perhaps older, Android smartphone to isolate the problem.