Loss of spaces between words when writing the word "I"

When I write the word “I” suddenly the spaces before and after that word disappear and the words around “I” merge together and become one word.

Here is an example: I wrote

…so blind that I am still… but in Scrivener it becomes…

“…so blind thatIam still…”

This also happens in textedit but it does not happen in Pages.

Please help!