I just noticed that the preview for Contextual Alternates doesn’t work right in the OTD.
My normal font looks like this:
I have alternative letters with the calt feature. As you can see, the calt box is not checked on the left side, yet the preview displays the alternative letters.
I’m 90% sure this once worked. Don’t know why it now doesn’t anymore.
You’ve enabled the more advanced Shaping Engine (_shaper), which behaves more like other software like Microsoft Word, Adobe InDesign, Serif Affinity Designer, and web browsers. This will process specific features (calt is one of them) in a specific order, even if they are not selected, and after that it will process all remaining active features.
This is also explained in the manual. You can click the Help button within the OpenType Designer dialog.
I must have clicked on that accidentally. Thanks!