Staff text disappears

I'm using staff text a lot, usually at the begging of the each measure to to write down a chord names. However it happens very often, that some staff text just disappears and I have to add it again. Usually I edit few next measures, and when I get back to previous, some of staff text is gone. It status on some measures, and it is missing on the another. Unfortunately I'm not able to say how exactly to reproduce it. But is happens quite regullary.