I encountered this problem where the survey-multi-choice plugin did not record which option was chosen, and was left empty in the data file (i.e., in the data the responses was shown as Q0: "", Q1: "", etc.). I used quotation marks inside the options, since the task was to choose between different verbal statements. However, I managed to fix this by removing the quotation marks.
I thought I would describe the problem here since I could not see it was mentioned anywhere else. I was able to work around this by using a different type of quotation marks (“ ” instead of "")
plugin version 2.0.0