Can't Undo Any Actions (Latest Update)

That pretty much sums up the situation. Let me know if you need any other details.

Thanks!

Which version exactly? Undo works for me in build 1246. Try the latest beta perhaps: Go to Glyphs > Preferences > Updates, activate both checkboxes and press the Update button.

Do you have any plugins active?

Apologies for the late reply. It turned out to be my computer, not the program. Sorry!

Can you explain what went wrong?