Doesn't work correctly from certain positions

[nullromo]

Most of the words can be toggled from any position within the word, but not always.

^ = cursor position in the examples below

enable -> disable

enable
     ^

disable can toggle from any position, while enable can toggle from any position except the final e.

disabled -> enabled

disabled
       ^

enabled can toggle from any position, while disabled can toggle from any position except the final d.

Jan -> Feb

-- Jan
   ^
-- enable

When I put my cursor on the J, the enable changes to disable for some reason. This also works like this

-- Jan
   ^
-- Feb
--
--
--
--
-- true

When I try to toggle the Jan from the a or the n, the true changes to false instead. When I try to toggle the Jan from the n, nothing happens.