I was stuck for almost 2 weeks on a button that would display, given a certain icon, and that would not display if it was another icon, although I checked the icons multiple times to make sure they existed.
A asked a co-worker for help. He looked at my code, couldn't figure out either. Called a 3rd co-worker. He looked at my code. "Yeah, seems right? ... Wait a second!" He found the problem.
... One FUCKING TYPO I had always overlooked, that was the name of the icon. 🤦