The h264 codec does fine after adding effects. There's something amiss locally. Do try another PC if you can.
Tests here used both the MOV and mp4 formats - each with h264.
Here's something else you can try.
Close Videopad, then use Windows Explorer (the file manager) to delete all files in these two folders...
"C:\Users\<PC Name>\AppData\Roaming\NCH Software\Components"
"C:\Program Files (x86)\NCH Software\Components" - or similar path minus the (x86)
Now reinstall the version of VP linked above.