In the latest release 1.3.21 (492), choosing an opentype feature from the dropdown at the very lower left of the Glyphs window no longer visibly takes effect on the text in the window.
What’s more, after choosing these features, putting the cursor back into the text and trying to type something new doesn’t work, it just moves the cursor through the text already there.
This was working in the immediately prior release.
Yikes, I wonder if this Glyphs file was corrupted. I reverted to the previous version of the application, and I’m seeing the same lack of response to choosing features, and it basically crashes when I try to do anything.
Can you send us the file?
support at this domain
Can you send me the .glyphs file?
I sent it, thanks for looking it over.
If you don’t get a reply soon, it must have crashed our machines so badly… 
The updated application file you sent is now working fine with this Glyphs file except that the automatic figure features aren’t working right. This is a typeface with osf as default, and after reading in the just-released manual that Glyphs can automatically handle setting up features for such a face, I renamed my glyphs and tried to generate the features. It worked perfectly in the other (italic) Glyphs file, but in this one it seems like Glyphs is not recognizing that my standard figures are osf (named without a suffix) and is thus not correctly generating features (e.g. not generating an lnum feature at all).
And similarly, if I create my own lnum feature, it will appear in the edit window dropdown, but has no effect on the displayed letters.