How can a stock post positive earnings and have a negative p/e? I’ve seen this with a few stocks and am a bit confused

Basically the title. I think I’m a pretty well educated casual investor, but this has always confused me.

For example: WBA last posted earnings well over a dollar a share and their next EPS projection is 0.66. Yet their p/e is showing -2.55. I’m sure this is just something I missed learning along the way, but I’m confused as to how you could ever have negative price/earning ratio if you have positive earnings.

Thanks in advance for the knowledge