I was able to troubleshoot and solve the problem on my own (amazing statement from someone with zero coding skills, though a rough understanding of how things work under the hood 
).
Yesterday, I had downloaded Bike 2 to see what folks were talking about and quickly found it overwhelming and just left it sitting in my applications folder. I moved it to the trash a few minutes ago and voilà , Shortcuts are working again.
Lesson learned: don’t keep a beta version of Bike on your device.