[Zubersoft]

Text files can be a little hit-or-miss because MobileSheets has to guess at what is a chord line versus a line of lyrics. It uses a simple calculation where it requires that a certain number of characters be valid chords or it will consider it a line of lyrics instead. So when you are adding the x4, two parts are chords (G and G/D) and one part is not (x4) so that is not high enough for it to consider it a line of chords. If you had more chords on the line, then it would recognize it correctly. I can also update the parsing so that it ignores a phrase starting with x followed by a number. 

If you want this to all work more reliably, you should consider switching to chord pro. The chord pro specification provides a lot more functionality, and having chords inside of brackets ensures that MobileSheets can easily recognize them. There are online converters that can help automate the conversion as well.

Mike