When having a poll of around 500 possible answers, you'll hit the default max_input_vars limit of 1000 in PHP. This makes it unable for the user to edit the poll (e.g. add options).
Sorry, thought this was the fix, appeared that on the system I tested the max_input_vars was indeed 1000, but on the development system it was more. Seems to be an issue that we can't overcome.
When having a poll of around 500 possible answers, you'll hit the default max_input_vars limit of 1000 in PHP. This makes it unable for the user to edit the poll (e.g. add options).
I will submit a pull request later.