Lines at start of time signature range deleted on change of previous time signature
First of all, I'm not entirely sure how to guarantee a reproduction but this is how it's happened to me.
I have a section (B) with dynamic markers in the second voice in 6/8 time. If I put 6/8 in a section which comes earlier than the B section and then remove the new time signature all the dynamic markers placed in the second voice (green) will disappear.
Generally, the issue seems to be with change of time signatures and I also noticed how only the second voice is affected by this issue. My B section repeats and I am unsure if the issue affects all repetitions or if it's just the next section that uses a second voice (green).