To schedule WhatsApp messages, there are two main requirements that have to be met so that auto-sending at the scheduled time is successful:
1. Accessibility: You need to first enable Accessibility for SKEDit
NB: On some android devices / OS, battery optimisation will automatically disable accessibility service, causing auto messages to fail at the scheduled time. To solve, please check point 3 below)
2. Screen-lock: You need to disable screen-lock, otherwise the app would not be able to access the device at the scheduled device to perform the auto-sending. Disabling differs depending on the device, for example on recent Samsung devices you can go to Settings > Screen lock > Set to "Swipe" or "None" (recommended). On Xiomi, you need to "turn off lock" from your device screen-lock settings, and if auto-sending still fails, you need to also enable "Skip screen lock" from developer options (on some other MIUI, found as "Skip Swipe Screen" in screen-lock settings).
NB: This is an external technical limitation that is outside of our control. Once it becomes feasible we will surely add it. We have done significant R&D to allow this workaround solution, at the compromise of screen-lock, and since the alternative is no automation at all, we thought it would be definitely worth it :)
If you still face failed message issues, please also try
3. Disable battery optimization: From the bottom of the WhatsApp scheduling screen, you can access "Change battery optimization". From there, you need to go to "All apps" > scroll down to find SKEDit > Disable. It should then show in the list of "disabled apps". (more info here: https://skedit.zendesk.com/hc/en-us/articles/360000057572-SKEDit-keeps-asking-me-to-enable-accessibility-but-i-already-did-what-can-i-do-https://skedit.zendesk.com/hc/en-us/articles/360000052971-How-to-enable-Accessibility-for-SKEDit)
In case it still fails, please contact us by submitting a ticket in the Help Center and we will look into it asap. Please make sure you attach a video screen record along with the ticket, showing the issue you are facing, starting from the scheduling process (FYI: from the video screen recorder app settings you can usually decrease video resolution and quality to 360p/2mbps, so that the size is small and can be easily sent via ticket/email firstname.lastname@example.org).