I have same problem. I made a "Start from Zero" App following this document;
http://help.easyar.com/EasyAR%20Sense%20Unity%20Plugin/Guides/Start-from-Zero.html
At first running ImageTarget Recognition work well. But once the window is closed, then run again but now doesn't work. After uninstalling the App and reinstall again, then run properly at first time only again. What's the reason?
Windows 10 / Unity 2019.4.8f1 / Android 10 / Pixel 4a