Couple things could be going on here. It's best to try each of these in order to address the compiling issue.
- Check your Google Play Services app and make sure it's up to date. This is the app we use to sync with your Drive account. Sometimes this doesn't get updated and causes a bunch of issues.
- This could just be a firmware hiccup. Which sadly happens on Android sometimes. Please try a hard restart of your phone and try to mash again. Turn it off and then back on basically.
- Make sure you have space available on your device. You'll need around 2mb per second for HD video and this should be on the device.
- The last idea, toggle on HARDWARE COMPILE in 1SE settings. It's at the bottom and will make 1SE try a different way to save videos.
Please keep in mind, compiling will happen in the background and depends on the processing speed of your device. The length of time you're trying to compile is also a variable. The more you're trying to put together, the longer it'll take.