The X99 TV box running HTS Tvheadend 4.3-2180 with LibreELEC Tvheadend-addon v12.0.0.3 appears to have a specific issue with autorecording and timer creation. When attempting to add new autorecs or timers via the Digital Video Recorder menus, the "Loading, please wait..." message displays briefly, but no further action occurs. The log does not show any relevant entries.
This issue is specific to the X99 setup, as the same Hauppauge WinTV-dualHD tuner and DVB-T connection work properly on a Raspberry Pi 4 running Tvheadend, allowing for successful EPG-based single and autorecordings. The core problem seems to lie within the X99's interaction with the Tvheadend interface for adding these scheduled tasks. Consider checking for specific hardware or operating system incompatibilities on the Rockchip RK3399-based device if traditional troubleshooting steps for Tvheadend software do not resolve it.