I'm having the same issue (created a forum account just for this).
I have some built-in snippets, but they do not conflict with my Alfred snippets. Could they still be causing the issue? Must I delete all my built-in snippets?
I also see similar behavior: I have to reboot or quit Alfred and restart so that the snippet behavior is normal again.
I do not use any other text expanders.
I have an Apple Keyboard (MacBook Pro (13-inch, 2017, Two Thunderbolt 3 ports) UK version).
I do not use any keyboard modifier apps
Thanks for the help : )