Forums are fun! 
Yes, they are. People show, up, say they have exactly the same problem, but it turns out that they have a completely differnt version of the software (2 major releases newer). The problem also occurs in a totally different question type (Array Numbers vs. Array (10 point)).
Forums are certainly fun.
Like Joffm. This problem was most probably a very specific problem of this user/installation. I don't know if there was a solution, because OP did not answer the questions of Denis, for example.
But let's get to it:
So now we figured out that you seem to use 3.17.1+190408.
I am not aware of such a bug being something general, but of course I am not aware of every single bug that exists in any of the many versions. But I would guess it is either something very specific to a few installations or it is specific to your survey.
According to Joffm's tests it seems not be a general problem of the current version of the 3.x branch either.
Did you test this with a simple survey, with just one question of the type Array Numbers with check boxes to check if it is a general problem with this type of question? Or has it only been tested within a more complex survey, where there could be other factors that cause this?
If so, please create a copy of this survey, delete all questions that are not relevant for the problem, export it and post it here so that we can check and see if the problem also occurs in our installations.
