@NathanCu How old is the Fire tablet you are running it on. I had seen several reports that the Webview it was using was not up to date enough. Although newer Fire tablets appeared to be OK.
To be honest the tablets did update when I turned them, they hadn’t been on in a long time.
Update: My Fire Tablets are running Fire OS 5.7.0.0, FKB 1.49.1 and when FKB starts it warns of an “Outdated version of Android Webview curr ver 59”