I am running Logic Pro 10.4.6 on Mac OS 10.13.6 and I am having problem with flex markers. Whenever I turn flex on, sometimes the flex markers appear, sometimes they don't, sometimes I go into FlexPitch, then into Flextime-Polyphonic and the lines appear, but then when I choose a quantization (like 1/16 note) the flex markers disappear and the file doesn't quantize. Any thoughts? Thanks!