Ipad apps won't install, just spin

Hi - my ipad mini 4 will no longer install or update any apps. When I click the download arrow to install or update any app, it just spins (sometimes briefly, sometimes for a long time) and then eventually the download button reappears, without having installed the app. I've tried everything I can think of, including updating to the latest OS, signing in and out of my Apple ID, rebooting many times, etc. I currently have an ipad with no apps (after installing the latest OS, even my previously installed apps disappeared), so it is pretty useless. Any ideas? Appreciate the help. Thanks!