Sorting of Group Exposed Filter Options

I'm trying to create a filter within Views of options A - Z based on the first letter of the node title. This is a glossary application so users need to sort by the first letter of the term. I can set up each option fine (using "A" "starts with" "A", "B" "starts with" "B", etc. through to Z). The problem is that when I save the filter, Views is re-sorting the options in non-alphabetical order and the resulting select menu seems a somewhat randomly ordered display of letter options.

I'm not sure whether this is the issue, but in trying to correct the re-sort, it looks like their are limited weight options (-10 to +10) and so multiple options are forced to have the same weight when setting up an alphabet-based sort. Regardless, I cannot get options A to Z to display in alphabetic order, as desired. Even after manually trying to resort the options into the correct order, Views still re-sorts the options out of sequence.