Apologies for the issues reported in 1.3 but I think I know what the problem is.
Seems that the WordPress plugin repo hasn't added all the files to the update and thus a number of issues are occurring.
For the time being, if you are happy to, grab the latest version from Github (https://github.com/WolfieZero/simply-poll) as this will have all the files and overrite the current
simply-poll folder in your
plugins directory. This won't delete the data from any of your current polls as these are stored in your WP database.
I'll try and get this sorted ASAP.