Quantize MIDI note length issue (SOLVED)

[delpaso]

Been having this problem for quite a while now, whereby whenever I try to quantize the length of notes in the piano roll, it'll either not change the length of the note at all or change it to a weird length.

Even though the checkbox is checked to allow notes to both shrink and grow, they only seem to grow. For instance, if I try to make a 1/8th note 1/16th in length, nothing will happen. However, when I set the same note to 1/4th, it'll grow fine.

It's so strange because this all used to work perfectly. Hoping someone can help, it's driving me crazy! Thanks!

Edit: Added screen grab - in this particular example, you'd expect to see all the notes changed to 1/64th, however all of the notes are still as long as they were before.